Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

23 files changed, 4779 insertions, 0 deletions

diff --git a/third_party/rust/neqo-crypto/src/aead.rs b/third_party/rust/neqo-crypto/src/aead.rs
new file mode 100644
index 0000000000..a2f009a403
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/aead.rs
@@ -0,0 +1,175 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    convert::{TryFrom, TryInto},
+    fmt,
+    ops::{Deref, DerefMut},
+    os::raw::{c_char, c_uint},
+    ptr::null_mut,
+};
+
+use crate::{
+    constants::{Cipher, Version},
+    err::Res,
+    experimental_api,
+    p11::{PK11SymKey, SymKey},
+    scoped_ptr,
+    ssl::{self, PRUint16, PRUint64, PRUint8, SSLAeadContext},
+};
+
+experimental_api!(SSL_MakeAead(
+    version: PRUint16,
+    cipher: PRUint16,
+    secret: *mut PK11SymKey,
+    label_prefix: *const c_char,
+    label_prefix_len: c_uint,
+    ctx: *mut *mut SSLAeadContext,
+));
+experimental_api!(SSL_AeadEncrypt(
+    ctx: *const SSLAeadContext,
+    counter: PRUint64,
+    aad: *const PRUint8,
+    aad_len: c_uint,
+    input: *const PRUint8,
+    input_len: c_uint,
+    output: *const PRUint8,
+    output_len: *mut c_uint,
+    max_output: c_uint
+));
+experimental_api!(SSL_AeadDecrypt(
+    ctx: *const SSLAeadContext,
+    counter: PRUint64,
+    aad: *const PRUint8,
+    aad_len: c_uint,
+    input: *const PRUint8,
+    input_len: c_uint,
+    output: *const PRUint8,
+    output_len: *mut c_uint,
+    max_output: c_uint
+));
+experimental_api!(SSL_DestroyAead(ctx: *mut SSLAeadContext));
+scoped_ptr!(AeadContext, SSLAeadContext, SSL_DestroyAead);
+
+pub struct RealAead {
+    ctx: AeadContext,
+}
+
+impl RealAead {
+    /// Create a new AEAD based on the indicated TLS version and cipher suite.
+    ///
+    /// # Errors
+    ///
+    /// Returns `Error` when the supporting NSS functions fail.
+    pub fn new(
+        _fuzzing: bool,
+        version: Version,
+        cipher: Cipher,
+        secret: &SymKey,
+        prefix: &str,
+    ) -> Res<Self> {
+        let s: *mut PK11SymKey = **secret;
+        unsafe { Self::from_raw(version, cipher, s, prefix) }
+    }
+
+    #[must_use]
+    #[allow(clippy::unused_self)]
+    pub fn expansion(&self) -> usize {
+        16
+    }
+
+    unsafe fn from_raw(
+        version: Version,
+        cipher: Cipher,
+        secret: *mut PK11SymKey,
+        prefix: &str,
+    ) -> Res<Self> {
+        let p = prefix.as_bytes();
+        let mut ctx: *mut ssl::SSLAeadContext = null_mut();
+        SSL_MakeAead(
+            version,
+            cipher,
+            secret,
+            p.as_ptr().cast(),
+            c_uint::try_from(p.len())?,
+            &mut ctx,
+        )?;
+        Ok(Self {
+            ctx: AeadContext::from_ptr(ctx)?,
+        })
+    }
+
+    /// Encrypt a plaintext.
+    ///
+    /// The space provided in `output` needs to be larger than `input` by
+    /// the value provided in `Aead::expansion`.
+    ///
+    /// # Errors
+    ///
+    /// If the input can't be protected or any input is too large for NSS.
+    pub fn encrypt<'a>(
+        &self,
+        count: u64,
+        aad: &[u8],
+        input: &[u8],
+        output: &'a mut [u8],
+    ) -> Res<&'a [u8]> {
+        let mut l: c_uint = 0;
+        unsafe {
+            SSL_AeadEncrypt(
+                *self.ctx,
+                count,
+                aad.as_ptr(),
+                c_uint::try_from(aad.len())?,
+                input.as_ptr(),
+                c_uint::try_from(input.len())?,
+                output.as_mut_ptr(),
+                &mut l,
+                c_uint::try_from(output.len())?,
+            )
+        }?;
+        Ok(&output[0..(l.try_into()?)])
+    }
+
+    /// Decrypt a ciphertext.
+    ///
+    /// Note that NSS insists upon having extra space available for decryption, so
+    /// the buffer for `output` should be the same length as `input`, even though
+    /// the final result will be shorter.
+    ///
+    /// # Errors
+    ///
+    /// If the input isn't authenticated or any input is too large for NSS.
+    pub fn decrypt<'a>(
+        &self,
+        count: u64,
+        aad: &[u8],
+        input: &[u8],
+        output: &'a mut [u8],
+    ) -> Res<&'a [u8]> {
+        let mut l: c_uint = 0;
+        unsafe {
+            SSL_AeadDecrypt(
+                *self.ctx,
+                count,
+                aad.as_ptr(),
+                c_uint::try_from(aad.len())?,
+                input.as_ptr(),
+                c_uint::try_from(input.len())?,
+                output.as_mut_ptr(),
+                &mut l,
+                c_uint::try_from(output.len())?,
+            )
+        }?;
+        Ok(&output[0..(l.try_into()?)])
+    }
+}
+
+impl fmt::Debug for RealAead {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "[AEAD Context]")
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/aead_fuzzing.rs b/third_party/rust/neqo-crypto/src/aead_fuzzing.rs
new file mode 100644
index 0000000000..4e5a6de07f
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/aead_fuzzing.rs
@@ -0,0 +1,103 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::fmt;
+
+use crate::{
+    constants::{Cipher, Version},
+    err::{sec::SEC_ERROR_BAD_DATA, Error, Res},
+    p11::SymKey,
+    RealAead,
+};
+
+pub const FIXED_TAG_FUZZING: &[u8] = &[0x0a; 16];
+
+pub struct FuzzingAead {
+    real: Option<RealAead>,
+}
+
+impl FuzzingAead {
+    pub fn new(
+        fuzzing: bool,
+        version: Version,
+        cipher: Cipher,
+        secret: &SymKey,
+        prefix: &str,
+    ) -> Res<Self> {
+        let real = if fuzzing {
+            None
+        } else {
+            Some(RealAead::new(false, version, cipher, secret, prefix)?)
+        };
+        Ok(Self { real })
+    }
+
+    #[must_use]
+    pub fn expansion(&self) -> usize {
+        if let Some(aead) = &self.real {
+            aead.expansion()
+        } else {
+            FIXED_TAG_FUZZING.len()
+        }
+    }
+
+    pub fn encrypt<'a>(
+        &self,
+        count: u64,
+        aad: &[u8],
+        input: &[u8],
+        output: &'a mut [u8],
+    ) -> Res<&'a [u8]> {
+        if let Some(aead) = &self.real {
+            return aead.encrypt(count, aad, input, output);
+        }
+
+        let l = input.len();
+        output[..l].copy_from_slice(input);
+        output[l..l + 16].copy_from_slice(FIXED_TAG_FUZZING);
+        Ok(&output[..l + 16])
+    }
+
+    pub fn decrypt<'a>(
+        &self,
+        count: u64,
+        aad: &[u8],
+        input: &[u8],
+        output: &'a mut [u8],
+    ) -> Res<&'a [u8]> {
+        if let Some(aead) = &self.real {
+            return aead.decrypt(count, aad, input, output);
+        }
+
+        if input.len() < FIXED_TAG_FUZZING.len() {
+            return Err(Error::from(SEC_ERROR_BAD_DATA));
+        }
+
+        let len_encrypted = input.len() - FIXED_TAG_FUZZING.len();
+        // Check that:
+        // 1) expansion is all zeros and
+        // 2) if the encrypted data is also supplied that at least some values are no zero
+        //    (otherwise padding will be interpreted as a valid packet)
+        if &input[len_encrypted..] == FIXED_TAG_FUZZING
+            && (len_encrypted == 0 || input[..len_encrypted].iter().any(|x| *x != 0x0))
+        {
+            output[..len_encrypted].copy_from_slice(&input[..len_encrypted]);
+            Ok(&output[..len_encrypted])
+        } else {
+            Err(Error::from(SEC_ERROR_BAD_DATA))
+        }
+    }
+}
+
+impl fmt::Debug for FuzzingAead {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if let Some(a) = &self.real {
+            a.fmt(f)
+        } else {
+            write!(f, "[FUZZING AEAD]")
+        }
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/agent.rs b/third_party/rust/neqo-crypto/src/agent.rs
new file mode 100644
index 0000000000..cd0bb4cb12
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/agent.rs
@@ -0,0 +1,1263 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    cell::RefCell,
+    convert::TryFrom,
+    ffi::{CStr, CString},
+    mem::{self, MaybeUninit},
+    ops::{Deref, DerefMut},
+    os::raw::{c_uint, c_void},
+    pin::Pin,
+    ptr::{null, null_mut},
+    rc::Rc,
+    time::Instant,
+};
+
+use neqo_common::{hex_snip_middle, hex_with_len, qdebug, qinfo, qtrace, qwarn};
+
+pub use crate::{
+    agentio::{as_c_void, Record, RecordList},
+    cert::CertificateInfo,
+};
+use crate::{
+    agentio::{AgentIo, METHODS},
+    assert_initialized,
+    auth::AuthenticationStatus,
+    constants::{
+        Alert, Cipher, Epoch, Extension, Group, SignatureScheme, Version, TLS_VERSION_1_3,
+    },
+    ech,
+    err::{is_blocked, secstatus_to_res, Error, PRErrorCode, Res},
+    ext::{ExtensionHandler, ExtensionTracker},
+    p11::{self, PrivateKey, PublicKey},
+    prio,
+    replay::AntiReplay,
+    secrets::SecretHolder,
+    ssl::{self, PRBool},
+    time::{Time, TimeHolder},
+};
+
+/// The maximum number of tickets to remember for a given connection.
+const MAX_TICKETS: usize = 4;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum HandshakeState {
+    New,
+    InProgress,
+    AuthenticationPending,
+    /// When encrypted client hello is enabled, the server might engage a fallback.
+    /// This is the status that is returned.  The included value is the public
+    /// name of the server, which should be used to validated the certificate.
+    EchFallbackAuthenticationPending(String),
+    Authenticated(PRErrorCode),
+    Complete(SecretAgentInfo),
+    Failed(Error),
+}
+
+impl HandshakeState {
+    #[must_use]
+    pub fn is_connected(&self) -> bool {
+        matches!(self, Self::Complete(_))
+    }
+
+    #[must_use]
+    pub fn is_final(&self) -> bool {
+        matches!(self, Self::Complete(_) | Self::Failed(_))
+    }
+
+    #[must_use]
+    pub fn authentication_needed(&self) -> bool {
+        matches!(
+            self,
+            Self::AuthenticationPending | Self::EchFallbackAuthenticationPending(_)
+        )
+    }
+}
+
+fn get_alpn(fd: *mut ssl::PRFileDesc, pre: bool) -> Res<Option<String>> {
+    let mut alpn_state = ssl::SSLNextProtoState::SSL_NEXT_PROTO_NO_SUPPORT;
+    let mut chosen = vec![0_u8; 255];
+    let mut chosen_len: c_uint = 0;
+    secstatus_to_res(unsafe {
+        ssl::SSL_GetNextProto(
+            fd,
+            &mut alpn_state,
+            chosen.as_mut_ptr(),
+            &mut chosen_len,
+            c_uint::try_from(chosen.len())?,
+        )
+    })?;
+
+    let alpn = match (pre, alpn_state) {
+        (true, ssl::SSLNextProtoState::SSL_NEXT_PROTO_EARLY_VALUE)
+        | (
+            false,
+            ssl::SSLNextProtoState::SSL_NEXT_PROTO_NEGOTIATED
+            | ssl::SSLNextProtoState::SSL_NEXT_PROTO_SELECTED,
+        ) => {
+            chosen.truncate(usize::try_from(chosen_len)?);
+            Some(match String::from_utf8(chosen) {
+                Ok(a) => a,
+                Err(_) => return Err(Error::InternalError),
+            })
+        }
+        _ => None,
+    };
+    qtrace!([format!("{fd:p}")], "got ALPN {:?}", alpn);
+    Ok(alpn)
+}
+
+pub struct SecretAgentPreInfo {
+    info: ssl::SSLPreliminaryChannelInfo,
+    alpn: Option<String>,
+}
+
+macro_rules! preinfo_arg {
+    ($v:ident, $m:ident, $f:ident: $t:ident $(,)?) => {
+        #[must_use]
+        pub fn $v(&self) -> Option<$t> {
+            match self.info.valuesSet & ssl::$m {
+                0 => None,
+                _ => Some($t::try_from(self.info.$f).unwrap()),
+            }
+        }
+    };
+}
+
+impl SecretAgentPreInfo {
+    fn new(fd: *mut ssl::PRFileDesc) -> Res<Self> {
+        let mut info: MaybeUninit<ssl::SSLPreliminaryChannelInfo> = MaybeUninit::uninit();
+        secstatus_to_res(unsafe {
+            ssl::SSL_GetPreliminaryChannelInfo(
+                fd,
+                info.as_mut_ptr(),
+                c_uint::try_from(mem::size_of::<ssl::SSLPreliminaryChannelInfo>())?,
+            )
+        })?;
+
+        Ok(Self {
+            info: unsafe { info.assume_init() },
+            alpn: get_alpn(fd, true)?,
+        })
+    }
+
+    preinfo_arg!(version, ssl_preinfo_version, protocolVersion: Version);
+    preinfo_arg!(cipher_suite, ssl_preinfo_cipher_suite, cipherSuite: Cipher);
+    preinfo_arg!(
+        early_data_cipher,
+        ssl_preinfo_0rtt_cipher_suite,
+        zeroRttCipherSuite: Cipher,
+    );
+
+    #[must_use]
+    pub fn early_data(&self) -> bool {
+        self.info.canSendEarlyData != 0
+    }
+
+    /// # Panics
+    ///
+    /// If `usize` is less than 32 bits and the value is too large.
+    #[must_use]
+    pub fn max_early_data(&self) -> usize {
+        usize::try_from(self.info.maxEarlyDataSize).unwrap()
+    }
+
+    /// Was ECH accepted.
+    #[must_use]
+    pub fn ech_accepted(&self) -> Option<bool> {
+        if self.info.valuesSet & ssl::ssl_preinfo_ech == 0 {
+            None
+        } else {
+            Some(self.info.echAccepted != 0)
+        }
+    }
+
+    /// Get the ECH public name that was used.  This will only be available
+    /// (that is, not `None`) if `ech_accepted()` returns `false`.
+    /// In this case, certificate validation needs to use this name rather
+    /// than the original name to validate the certificate.  If
+    /// that validation passes (that is, `SecretAgent::authenticated` is called
+    /// with `AuthenticationStatus::Ok`), then the handshake will still fail.
+    /// After the failed handshake, the state will be `Error::EchRetry`,
+    /// which contains a valid ECH configuration.
+    ///
+    /// # Errors
+    ///
+    /// When the public name is not valid UTF-8.  (Note: names should be ASCII.)
+    pub fn ech_public_name(&self) -> Res<Option<&str>> {
+        if self.info.valuesSet & ssl::ssl_preinfo_ech == 0 || self.info.echPublicName.is_null() {
+            Ok(None)
+        } else {
+            let n = unsafe { CStr::from_ptr(self.info.echPublicName) };
+            Ok(Some(n.to_str()?))
+        }
+    }
+
+    #[must_use]
+    pub fn alpn(&self) -> Option<&String> {
+        self.alpn.as_ref()
+    }
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct SecretAgentInfo {
+    version: Version,
+    cipher: Cipher,
+    group: Group,
+    resumed: bool,
+    early_data: bool,
+    ech_accepted: bool,
+    alpn: Option<String>,
+    signature_scheme: SignatureScheme,
+}
+
+impl SecretAgentInfo {
+    fn new(fd: *mut ssl::PRFileDesc) -> Res<Self> {
+        let mut info: MaybeUninit<ssl::SSLChannelInfo> = MaybeUninit::uninit();
+        secstatus_to_res(unsafe {
+            ssl::SSL_GetChannelInfo(
+                fd,
+                info.as_mut_ptr(),
+                c_uint::try_from(mem::size_of::<ssl::SSLChannelInfo>())?,
+            )
+        })?;
+        let info = unsafe { info.assume_init() };
+        Ok(Self {
+            version: info.protocolVersion,
+            cipher: info.cipherSuite,
+            group: Group::try_from(info.keaGroup)?,
+            resumed: info.resumed != 0,
+            early_data: info.earlyDataAccepted != 0,
+            ech_accepted: info.echAccepted != 0,
+            alpn: get_alpn(fd, false)?,
+            signature_scheme: SignatureScheme::try_from(info.signatureScheme)?,
+        })
+    }
+    #[must_use]
+    pub fn version(&self) -> Version {
+        self.version
+    }
+    #[must_use]
+    pub fn cipher_suite(&self) -> Cipher {
+        self.cipher
+    }
+    #[must_use]
+    pub fn key_exchange(&self) -> Group {
+        self.group
+    }
+    #[must_use]
+    pub fn resumed(&self) -> bool {
+        self.resumed
+    }
+    #[must_use]
+    pub fn early_data_accepted(&self) -> bool {
+        self.early_data
+    }
+    #[must_use]
+    pub fn ech_accepted(&self) -> bool {
+        self.ech_accepted
+    }
+    #[must_use]
+    pub fn alpn(&self) -> Option<&String> {
+        self.alpn.as_ref()
+    }
+    #[must_use]
+    pub fn signature_scheme(&self) -> SignatureScheme {
+        self.signature_scheme
+    }
+}
+
+/// `SecretAgent` holds the common parts of client and server.
+#[derive(Debug)]
+#[allow(clippy::module_name_repetitions)]
+pub struct SecretAgent {
+    fd: *mut ssl::PRFileDesc,
+    secrets: SecretHolder,
+    raw: Option<bool>,
+    io: Pin<Box<AgentIo>>,
+    state: HandshakeState,
+
+    /// Records whether authentication of certificates is required.
+    auth_required: Pin<Box<bool>>,
+    /// Records any fatal alert that is sent by the stack.
+    alert: Pin<Box<Option<Alert>>>,
+    /// The current time.
+    now: TimeHolder,
+
+    extension_handlers: Vec<ExtensionTracker>,
+
+    /// The encrypted client hello (ECH) configuration that is in use.
+    /// Empty if ECH is not enabled.
+    ech_config: Vec<u8>,
+}
+
+impl SecretAgent {
+    fn new() -> Res<Self> {
+        let mut io = Box::pin(AgentIo::new());
+        let fd = Self::create_fd(&mut io)?;
+        Ok(Self {
+            fd,
+            secrets: SecretHolder::default(),
+            raw: None,
+            io,
+            state: HandshakeState::New,
+
+            auth_required: Box::pin(false),
+            alert: Box::pin(None),
+            now: TimeHolder::default(),
+
+            extension_handlers: Vec::new(),
+
+            ech_config: Vec::new(),
+        })
+    }
+
+    // Create a new SSL file descriptor.
+    //
+    // Note that we create separate bindings for PRFileDesc as both
+    // ssl::PRFileDesc and prio::PRFileDesc.  This keeps the bindings
+    // minimal, but it means that the two forms need casts to translate
+    // between them.  ssl::PRFileDesc is left as an opaque type, as the
+    // ssl::SSL_* APIs only need an opaque type.
+    fn create_fd(io: &mut Pin<Box<AgentIo>>) -> Res<*mut ssl::PRFileDesc> {
+        assert_initialized();
+        let label = CString::new("sslwrapper")?;
+        let id = unsafe { prio::PR_GetUniqueIdentity(label.as_ptr()) };
+
+        let base_fd = unsafe { prio::PR_CreateIOLayerStub(id, METHODS) };
+        if base_fd.is_null() {
+            return Err(Error::CreateSslSocket);
+        }
+        let fd = unsafe {
+            (*base_fd).secret = as_c_void(io).cast();
+            ssl::SSL_ImportFD(null_mut(), base_fd.cast())
+        };
+        if fd.is_null() {
+            unsafe { prio::PR_Close(base_fd) };
+            return Err(Error::CreateSslSocket);
+        }
+        Ok(fd)
+    }
+
+    unsafe extern "C" fn auth_complete_hook(
+        arg: *mut c_void,
+        _fd: *mut ssl::PRFileDesc,
+        _check_sig: ssl::PRBool,
+        _is_server: ssl::PRBool,
+    ) -> ssl::SECStatus {
+        let auth_required_ptr = arg.cast::<bool>();
+        *auth_required_ptr = true;
+        // NSS insists on getting SECWouldBlock here rather than accepting
+        // the usual combination of PR_WOULD_BLOCK_ERROR and SECFailure.
+        ssl::_SECStatus_SECWouldBlock
+    }
+
+    unsafe extern "C" fn alert_sent_cb(
+        fd: *const ssl::PRFileDesc,
+        arg: *mut c_void,
+        alert: *const ssl::SSLAlert,
+    ) {
+        let alert = alert.as_ref().unwrap();
+        if alert.level == 2 {
+            // Fatal alerts demand attention.
+            let st = arg.cast::<Option<Alert>>().as_mut().unwrap();
+            if st.is_none() {
+                *st = Some(alert.description);
+            } else {
+                qwarn!([format!("{fd:p}")], "duplicate alert {}", alert.description);
+            }
+        }
+    }
+
+    // Ready this for connecting.
+    fn ready(&mut self, is_server: bool, grease: bool) -> Res<()> {
+        secstatus_to_res(unsafe {
+            ssl::SSL_AuthCertificateHook(
+                self.fd,
+                Some(Self::auth_complete_hook),
+                as_c_void(&mut self.auth_required),
+            )
+        })?;
+
+        secstatus_to_res(unsafe {
+            ssl::SSL_AlertSentCallback(
+                self.fd,
+                Some(Self::alert_sent_cb),
+                as_c_void(&mut self.alert),
+            )
+        })?;
+
+        self.now.bind(self.fd)?;
+        self.configure(grease)?;
+        secstatus_to_res(unsafe { ssl::SSL_ResetHandshake(self.fd, ssl::PRBool::from(is_server)) })
+    }
+
+    /// Default configuration.
+    ///
+    /// # Errors
+    ///
+    /// If `set_version_range` fails.
+    fn configure(&mut self, grease: bool) -> Res<()> {
+        self.set_version_range(TLS_VERSION_1_3, TLS_VERSION_1_3)?;
+        self.set_option(ssl::Opt::Locking, false)?;
+        self.set_option(ssl::Opt::Tickets, false)?;
+        self.set_option(ssl::Opt::OcspStapling, true)?;
+        if let Err(e) = self.set_option(ssl::Opt::Grease, grease) {
+            // Until NSS supports greasing, it's OK to fail here.
+            qinfo!([self], "Failed to enable greasing {:?}", e);
+        }
+        Ok(())
+    }
+
+    /// Set the versions that are supported.
+    ///
+    /// # Errors
+    ///
+    /// If the range of versions isn't supported.
+    pub fn set_version_range(&mut self, min: Version, max: Version) -> Res<()> {
+        let range = ssl::SSLVersionRange { min, max };
+        secstatus_to_res(unsafe { ssl::SSL_VersionRangeSet(self.fd, &range) })
+    }
+
+    /// Enable a set of ciphers.  Note that the order of these is not respected.
+    ///
+    /// # Errors
+    ///
+    /// If NSS can't enable or disable ciphers.
+    pub fn set_ciphers(&mut self, ciphers: &[Cipher]) -> Res<()> {
+        if self.state != HandshakeState::New {
+            qwarn!([self], "Cannot enable ciphers in state {:?}", self.state);
+            return Err(Error::InternalError);
+        }
+
+        let all_ciphers = unsafe { ssl::SSL_GetImplementedCiphers() };
+        let cipher_count = usize::from(unsafe { ssl::SSL_GetNumImplementedCiphers() });
+        for i in 0..cipher_count {
+            let p = all_ciphers.wrapping_add(i);
+            secstatus_to_res(unsafe {
+                ssl::SSL_CipherPrefSet(self.fd, i32::from(*p), ssl::PRBool::from(false))
+            })?;
+        }
+
+        for c in ciphers {
+            secstatus_to_res(unsafe {
+                ssl::SSL_CipherPrefSet(self.fd, i32::from(*c), ssl::PRBool::from(true))
+            })?;
+        }
+        Ok(())
+    }
+
+    /// Set key exchange groups.
+    ///
+    /// # Errors
+    ///
+    /// If the underlying API fails (which shouldn't happen).
+    pub fn set_groups(&mut self, groups: &[Group]) -> Res<()> {
+        // SSLNamedGroup is a different size to Group, so copy one by one.
+        let group_vec: Vec<_> = groups
+            .iter()
+            .map(|&g| ssl::SSLNamedGroup::Type::from(g))
+            .collect();
+
+        let ptr = group_vec.as_slice().as_ptr();
+        secstatus_to_res(unsafe {
+            ssl::SSL_NamedGroupConfig(self.fd, ptr, c_uint::try_from(group_vec.len())?)
+        })
+    }
+
+    /// Set the number of additional key shares that will be sent in the client hello
+    ///
+    /// # Errors
+    ///
+    /// If the underlying API fails (which shouldn't happen).
+    pub fn send_additional_key_shares(&mut self, count: usize) -> Res<()> {
+        secstatus_to_res(unsafe {
+            ssl::SSL_SendAdditionalKeyShares(self.fd, c_uint::try_from(count)?)
+        })
+    }
+
+    /// Set TLS options.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the option or option value is invalid; i.e., never.
+    pub fn set_option(&mut self, opt: ssl::Opt, value: bool) -> Res<()> {
+        opt.set(self.fd, value)
+    }
+
+    /// Enable 0-RTT.
+    ///
+    /// # Errors
+    ///
+    /// See `set_option`.
+    pub fn enable_0rtt(&mut self) -> Res<()> {
+        self.set_option(ssl::Opt::EarlyData, true)
+    }
+
+    /// Disable the `EndOfEarlyData` message.
+    ///
+    /// # Errors
+    ///
+    /// See `set_option`.
+    pub fn disable_end_of_early_data(&mut self) -> Res<()> {
+        self.set_option(ssl::Opt::SuppressEndOfEarlyData, true)
+    }
+
+    /// `set_alpn` sets a list of preferred protocols, starting with the most preferred.
+    /// Though ALPN [RFC7301] permits octet sequences, this only allows for UTF-8-encoded
+    /// strings.
+    ///
+    /// This asserts if no items are provided, or if any individual item is longer than
+    /// 255 octets in length.
+    ///
+    /// # Errors
+    ///
+    /// This should always panic rather than return an error.
+    ///
+    /// # Panics
+    ///
+    /// If any of the provided `protocols` are more than 255 bytes long.
+    ///
+    /// [RFC7301]: https://datatracker.ietf.org/doc/html/rfc7301
+    pub fn set_alpn(&mut self, protocols: &[impl AsRef<str>]) -> Res<()> {
+        // Validate and set length.
+        let mut encoded_len = protocols.len();
+        for v in protocols {
+            assert!(v.as_ref().len() < 256);
+            assert!(!v.as_ref().is_empty());
+            encoded_len += v.as_ref().len();
+        }
+
+        // Prepare to encode.
+        let mut encoded = Vec::with_capacity(encoded_len);
+        let mut add = |v: &str| {
+            if let Ok(s) = u8::try_from(v.len()) {
+                encoded.push(s);
+                encoded.extend_from_slice(v.as_bytes());
+            }
+        };
+
+        // NSS inherited an idiosyncratic API as a result of having implemented NPN
+        // before ALPN.  For that reason, we need to put the "best" option last.
+        let (first, rest) = protocols
+            .split_first()
+            .expect("at least one ALPN value needed");
+        for v in rest {
+            add(v.as_ref());
+        }
+        add(first.as_ref());
+        assert_eq!(encoded_len, encoded.len());
+
+        // Now give the result to NSS.
+        secstatus_to_res(unsafe {
+            ssl::SSL_SetNextProtoNego(
+                self.fd,
+                encoded.as_slice().as_ptr(),
+                c_uint::try_from(encoded.len())?,
+            )
+        })
+    }
+
+    /// Install an extension handler.
+    ///
+    /// This can be called multiple times with different values for `ext`.  The handler is provided
+    /// as `Rc<RefCell<dyn T>>` so that the caller is able to hold a reference to the handler
+    /// and later access any state that it accumulates.
+    ///
+    /// # Errors
+    ///
+    /// When the extension handler can't be successfully installed.
+    pub fn extension_handler(
+        &mut self,
+        ext: Extension,
+        handler: Rc<RefCell<dyn ExtensionHandler>>,
+    ) -> Res<()> {
+        let tracker = unsafe { ExtensionTracker::new(self.fd, ext, handler) }?;
+        self.extension_handlers.push(tracker);
+        Ok(())
+    }
+
+    // This function tracks whether handshake() or handshake_raw() was used
+    // and prevents the other from being used.
+    fn set_raw(&mut self, r: bool) -> Res<()> {
+        if self.raw.is_none() {
+            self.secrets.register(self.fd)?;
+            self.raw = Some(r);
+            Ok(())
+        } else if self.raw.unwrap() == r {
+            Ok(())
+        } else {
+            Err(Error::MixedHandshakeMethod)
+        }
+    }
+
+    /// Get information about the connection.
+    /// This includes the version, ciphersuite, and ALPN.
+    ///
+    /// Calling this function returns None until the connection is complete.
+    #[must_use]
+    pub fn info(&self) -> Option<&SecretAgentInfo> {
+        match self.state {
+            HandshakeState::Complete(ref info) => Some(info),
+            _ => None,
+        }
+    }
+
+    /// Get any preliminary information about the status of the connection.
+    ///
+    /// This includes whether 0-RTT was accepted and any information related to that.
+    /// Calling this function collects all the relevant information.
+    ///
+    /// # Errors
+    ///
+    /// When the underlying socket functions fail.
+    pub fn preinfo(&self) -> Res<SecretAgentPreInfo> {
+        SecretAgentPreInfo::new(self.fd)
+    }
+
+    /// Get the peer's certificate chain.
+    #[must_use]
+    pub fn peer_certificate(&self) -> Option<CertificateInfo> {
+        CertificateInfo::new(self.fd)
+    }
+
+    /// Return any fatal alert that the TLS stack might have sent.
+    #[must_use]
+    pub fn alert(&self) -> Option<&Alert> {
+        (*self.alert).as_ref()
+    }
+
+    /// Call this function to mark the peer as authenticated.
+    ///
+    /// # Panics
+    ///
+    /// If the handshake doesn't need to be authenticated.
+    pub fn authenticated(&mut self, status: AuthenticationStatus) {
+        assert!(self.state.authentication_needed());
+        *self.auth_required = false;
+        self.state = HandshakeState::Authenticated(status.into());
+    }
+
+    fn capture_error<T>(&mut self, res: Res<T>) -> Res<T> {
+        if let Err(e) = res {
+            let e = ech::convert_ech_error(self.fd, e);
+            qwarn!([self], "error: {:?}", e);
+            self.state = HandshakeState::Failed(e.clone());
+            Err(e)
+        } else {
+            res
+        }
+    }
+
+    fn update_state(&mut self, res: Res<()>) -> Res<()> {
+        self.state = if is_blocked(&res) {
+            if *self.auth_required {
+                self.preinfo()?.ech_public_name()?.map_or(
+                    HandshakeState::AuthenticationPending,
+                    |public_name| {
+                        HandshakeState::EchFallbackAuthenticationPending(public_name.to_owned())
+                    },
+                )
+            } else {
+                HandshakeState::InProgress
+            }
+        } else {
+            self.capture_error(res)?;
+            let info = self.capture_error(SecretAgentInfo::new(self.fd))?;
+            HandshakeState::Complete(info)
+        };
+        qinfo!([self], "state -> {:?}", self.state);
+        Ok(())
+    }
+
+    /// Drive the TLS handshake, taking bytes from `input` and putting
+    /// any bytes necessary into `output`.
+    /// This takes the current time as `now`.
+    /// On success a tuple of a `HandshakeState` and usize indicate whether the handshake
+    /// is complete and how many bytes were written to `output`, respectively.
+    /// If the state is `HandshakeState::AuthenticationPending`, then ONLY call this
+    /// function if you want to proceed, because this will mark the certificate as OK.
+    ///
+    /// # Errors
+    ///
+    /// When the handshake fails this returns an error.
+    pub fn handshake(&mut self, now: Instant, input: &[u8]) -> Res<Vec<u8>> {
+        self.now.set(now)?;
+        self.set_raw(false)?;
+
+        let rv = {
+            // Within this scope, _h maintains a mutable reference to self.io.
+            let _h = self.io.wrap(input);
+            match self.state {
+                HandshakeState::Authenticated(ref err) => unsafe {
+                    ssl::SSL_AuthCertificateComplete(self.fd, *err)
+                },
+                _ => unsafe { ssl::SSL_ForceHandshake(self.fd) },
+            }
+        };
+        // Take before updating state so that we leave the output buffer empty
+        // even if there is an error.
+        let output = self.io.take_output();
+        self.update_state(secstatus_to_res(rv))?;
+        Ok(output)
+    }
+
+    /// Setup to receive records for raw handshake functions.
+    fn setup_raw(&mut self) -> Res<Pin<Box<RecordList>>> {
+        self.set_raw(true)?;
+        self.capture_error(RecordList::setup(self.fd))
+    }
+
+    /// Drive the TLS handshake, but get the raw content of records, not
+    /// protected records as bytes. This function is incompatible with
+    /// `handshake()`; use either this or `handshake()` exclusively.
+    ///
+    /// Ideally, this only includes records from the current epoch.
+    /// If you send data from multiple epochs, you might end up being sad.
+    ///
+    /// # Errors
+    ///
+    /// When the handshake fails this returns an error.
+    pub fn handshake_raw(&mut self, now: Instant, input: Option<Record>) -> Res<RecordList> {
+        self.now.set(now)?;
+        let records = self.setup_raw()?;
+
+        // Fire off any authentication we might need to complete.
+        if let HandshakeState::Authenticated(ref err) = self.state {
+            let result =
+                secstatus_to_res(unsafe { ssl::SSL_AuthCertificateComplete(self.fd, *err) });
+            qdebug!([self], "SSL_AuthCertificateComplete: {:?}", result);
+            // This should return SECSuccess, so don't use update_state().
+            self.capture_error(result)?;
+        }
+
+        // Feed in any records.
+        if let Some(rec) = input {
+            self.capture_error(rec.write(self.fd))?;
+        }
+
+        // Drive the handshake once more.
+        let rv = secstatus_to_res(unsafe { ssl::SSL_ForceHandshake(self.fd) });
+        self.update_state(rv)?;
+
+        Ok(*Pin::into_inner(records))
+    }
+
+    /// # Panics
+    ///
+    /// If setup fails.
+    #[allow(unknown_lints, clippy::branches_sharing_code)]
+    pub fn close(&mut self) {
+        // It should be safe to close multiple times.
+        if self.fd.is_null() {
+            return;
+        }
+        if let Some(true) = self.raw {
+            // Need to hold the record list in scope until the close is done.
+            let _records = self.setup_raw().expect("Can only close");
+            unsafe { prio::PR_Close(self.fd.cast()) };
+        } else {
+            // Need to hold the IO wrapper in scope until the close is done.
+            let _io = self.io.wrap(&[]);
+            unsafe { prio::PR_Close(self.fd.cast()) };
+        };
+        let _output = self.io.take_output();
+        self.fd = null_mut();
+    }
+
+    /// State returns the status of the handshake.
+    #[must_use]
+    pub fn state(&self) -> &HandshakeState {
+        &self.state
+    }
+
+    /// Take a read secret.  This will only return a non-`None` value once.
+    #[must_use]
+    pub fn read_secret(&mut self, epoch: Epoch) -> Option<p11::SymKey> {
+        self.secrets.take_read(epoch)
+    }
+
+    /// Take a write secret.
+    #[must_use]
+    pub fn write_secret(&mut self, epoch: Epoch) -> Option<p11::SymKey> {
+        self.secrets.take_write(epoch)
+    }
+
+    /// Get the active ECH configuration, which is empty if ECH is disabled.
+    #[must_use]
+    pub fn ech_config(&self) -> &[u8] {
+        &self.ech_config
+    }
+}
+
+impl Drop for SecretAgent {
+    fn drop(&mut self) {
+        self.close();
+    }
+}
+
+impl ::std::fmt::Display for SecretAgent {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "Agent {:p}", self.fd)
+    }
+}
+
+#[derive(Debug, PartialOrd, Ord, PartialEq, Eq, Clone)]
+pub struct ResumptionToken {
+    token: Vec<u8>,
+    expiration_time: Instant,
+}
+
+impl AsRef<[u8]> for ResumptionToken {
+    fn as_ref(&self) -> &[u8] {
+        &self.token
+    }
+}
+
+impl ResumptionToken {
+    #[must_use]
+    pub fn new(token: Vec<u8>, expiration_time: Instant) -> Self {
+        Self {
+            token,
+            expiration_time,
+        }
+    }
+
+    #[must_use]
+    pub fn expiration_time(&self) -> Instant {
+        self.expiration_time
+    }
+}
+
+/// A TLS Client.
+#[derive(Debug)]
+#[allow(
+    renamed_and_removed_lints,
+    clippy::box_vec,
+    unknown_lints,
+    clippy::box_collection
+)] // We need the Box.
+pub struct Client {
+    agent: SecretAgent,
+
+    /// The name of the server we're attempting a connection to.
+    server_name: String,
+    /// Records the resumption tokens we've received.
+    resumption: Pin<Box<Vec<ResumptionToken>>>,
+}
+
+impl Client {
+    /// Create a new client agent.
+    ///
+    /// # Errors
+    ///
+    /// Errors returned if the socket can't be created or configured.
+    pub fn new(server_name: impl Into<String>, grease: bool) -> Res<Self> {
+        let server_name = server_name.into();
+        let mut agent = SecretAgent::new()?;
+        let url = CString::new(server_name.as_bytes())?;
+        secstatus_to_res(unsafe { ssl::SSL_SetURL(agent.fd, url.as_ptr()) })?;
+        agent.ready(false, grease)?;
+        let mut client = Self {
+            agent,
+            server_name,
+            resumption: Box::pin(Vec::new()),
+        };
+        client.ready()?;
+        Ok(client)
+    }
+
+    unsafe extern "C" fn resumption_token_cb(
+        fd: *mut ssl::PRFileDesc,
+        token: *const u8,
+        len: c_uint,
+        arg: *mut c_void,
+    ) -> ssl::SECStatus {
+        let mut info: MaybeUninit<ssl::SSLResumptionTokenInfo> = MaybeUninit::uninit();
+        if ssl::SSL_GetResumptionTokenInfo(
+            token,
+            len,
+            info.as_mut_ptr(),
+            c_uint::try_from(mem::size_of::<ssl::SSLResumptionTokenInfo>()).unwrap(),
+        )
+        .is_err()
+        {
+            // Ignore the token.
+            return ssl::SECSuccess;
+        }
+        let expiration_time = info.assume_init().expirationTime;
+        if ssl::SSL_DestroyResumptionTokenInfo(info.as_mut_ptr()).is_err() {
+            // Ignore the token.
+            return ssl::SECSuccess;
+        }
+        let resumption = arg.cast::<Vec<ResumptionToken>>().as_mut().unwrap();
+        let len = usize::try_from(len).unwrap();
+        let mut v = Vec::with_capacity(len);
+        v.extend_from_slice(std::slice::from_raw_parts(token, len));
+        qinfo!(
+            [format!("{fd:p}")],
+            "Got resumption token {}",
+            hex_snip_middle(&v)
+        );
+
+        if resumption.len() >= MAX_TICKETS {
+            resumption.remove(0);
+        }
+        if let Ok(t) = Time::try_from(expiration_time) {
+            resumption.push(ResumptionToken::new(v, *t));
+        }
+        ssl::SECSuccess
+    }
+
+    #[must_use]
+    pub fn server_name(&self) -> &str {
+        &self.server_name
+    }
+
+    fn ready(&mut self) -> Res<()> {
+        let fd = self.fd;
+        unsafe {
+            ssl::SSL_SetResumptionTokenCallback(
+                fd,
+                Some(Self::resumption_token_cb),
+                as_c_void(&mut self.resumption),
+            )
+        }
+    }
+
+    /// Take a resumption token.
+    #[must_use]
+    pub fn resumption_token(&mut self) -> Option<ResumptionToken> {
+        (*self.resumption).pop()
+    }
+
+    /// Check if there are more resumption tokens.
+    #[must_use]
+    pub fn has_resumption_token(&self) -> bool {
+        !(*self.resumption).is_empty()
+    }
+
+    /// Enable resumption, using a token previously provided.
+    ///
+    /// # Errors
+    ///
+    /// Error returned when the resumption token is invalid or
+    /// the socket is not able to use the value.
+    pub fn enable_resumption(&mut self, token: impl AsRef<[u8]>) -> Res<()> {
+        unsafe {
+            ssl::SSL_SetResumptionToken(
+                self.agent.fd,
+                token.as_ref().as_ptr(),
+                c_uint::try_from(token.as_ref().len())?,
+            )
+        }
+    }
+
+    /// Enable encrypted client hello (ECH), using the encoded `ECHConfigList`.
+    ///
+    /// When ECH is enabled, a client needs to look for `Error::EchRetry` as a
+    /// failure code.  If `Error::EchRetry` is received when connecting, the
+    /// connection attempt should be retried and the included value provided
+    /// to this function (instead of what is received from DNS).
+    ///
+    /// Calling this function with an empty value for `ech_config_list` enables
+    /// ECH greasing.  When that is done, there is no need to look for `EchRetry`
+    ///
+    /// # Errors
+    ///
+    /// Error returned when the configuration is invalid.
+    pub fn enable_ech(&mut self, ech_config_list: impl AsRef<[u8]>) -> Res<()> {
+        let config = ech_config_list.as_ref();
+        qdebug!([self], "Enable ECH for a server: {}", hex_with_len(config));
+        self.ech_config = Vec::from(config);
+        if config.is_empty() {
+            unsafe { ech::SSL_EnableTls13GreaseEch(self.agent.fd, PRBool::from(true)) }
+        } else {
+            unsafe {
+                ech::SSL_SetClientEchConfigs(
+                    self.agent.fd,
+                    config.as_ptr(),
+                    c_uint::try_from(config.len())?,
+                )
+            }
+        }
+    }
+}
+
+impl Deref for Client {
+    type Target = SecretAgent;
+    #[must_use]
+    fn deref(&self) -> &SecretAgent {
+        &self.agent
+    }
+}
+
+impl DerefMut for Client {
+    fn deref_mut(&mut self) -> &mut SecretAgent {
+        &mut self.agent
+    }
+}
+
+impl ::std::fmt::Display for Client {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "Client {:p}", self.agent.fd)
+    }
+}
+
+/// `ZeroRttCheckResult` encapsulates the options for handling a `ClientHello`.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum ZeroRttCheckResult {
+    /// Accept 0-RTT.
+    Accept,
+    /// Reject 0-RTT, but continue the handshake normally.
+    Reject,
+    /// Send HelloRetryRequest (probably not needed for QUIC).
+    HelloRetryRequest(Vec<u8>),
+    /// Fail the handshake.
+    Fail,
+}
+
+/// A `ZeroRttChecker` is used by the agent to validate the application token (as provided by
+/// `send_ticket`)
+pub trait ZeroRttChecker: std::fmt::Debug + std::marker::Unpin {
+    fn check(&self, token: &[u8]) -> ZeroRttCheckResult;
+}
+
+/// Using `AllowZeroRtt` for the implementation of `ZeroRttChecker` means
+/// accepting 0-RTT always.  This generally isn't a great idea, so this
+/// generates a strong warning when it is used.
+#[derive(Debug)]
+pub struct AllowZeroRtt {}
+impl ZeroRttChecker for AllowZeroRtt {
+    fn check(&self, _token: &[u8]) -> ZeroRttCheckResult {
+        qwarn!("AllowZeroRtt accepting 0-RTT");
+        ZeroRttCheckResult::Accept
+    }
+}
+
+#[derive(Debug)]
+struct ZeroRttCheckState {
+    checker: Pin<Box<dyn ZeroRttChecker>>,
+}
+
+impl ZeroRttCheckState {
+    pub fn new(checker: Box<dyn ZeroRttChecker>) -> Self {
+        Self {
+            checker: Pin::new(checker),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Server {
+    agent: SecretAgent,
+    /// This holds the HRR callback context.
+    zero_rtt_check: Option<Pin<Box<ZeroRttCheckState>>>,
+}
+
+impl Server {
+    /// Create a new server agent.
+    ///
+    /// # Errors
+    ///
+    /// Errors returned when NSS fails.
+    pub fn new(certificates: &[impl AsRef<str>]) -> Res<Self> {
+        let mut agent = SecretAgent::new()?;
+
+        for n in certificates {
+            let c = CString::new(n.as_ref())?;
+            let cert_ptr = unsafe { p11::PK11_FindCertFromNickname(c.as_ptr(), null_mut()) };
+            let Ok(cert) = p11::Certificate::from_ptr(cert_ptr) else {
+                return Err(Error::CertificateLoading);
+            };
+            let key_ptr = unsafe { p11::PK11_FindKeyByAnyCert(*cert, null_mut()) };
+            let Ok(key) = p11::PrivateKey::from_ptr(key_ptr) else {
+                return Err(Error::CertificateLoading);
+            };
+            secstatus_to_res(unsafe {
+                ssl::SSL_ConfigServerCert(agent.fd, *cert, *key, null(), 0)
+            })?;
+        }
+
+        agent.ready(true, true)?;
+        Ok(Self {
+            agent,
+            zero_rtt_check: None,
+        })
+    }
+
+    unsafe extern "C" fn hello_retry_cb(
+        first_hello: PRBool,
+        client_token: *const u8,
+        client_token_len: c_uint,
+        retry_token: *mut u8,
+        retry_token_len: *mut c_uint,
+        retry_token_max: c_uint,
+        arg: *mut c_void,
+    ) -> ssl::SSLHelloRetryRequestAction::Type {
+        if first_hello == 0 {
+            // On the second ClientHello after HelloRetryRequest, skip checks.
+            return ssl::SSLHelloRetryRequestAction::ssl_hello_retry_accept;
+        }
+
+        let check_state = arg.cast::<ZeroRttCheckState>().as_mut().unwrap();
+        let token = if client_token.is_null() {
+            &[]
+        } else {
+            std::slice::from_raw_parts(client_token, usize::try_from(client_token_len).unwrap())
+        };
+        match check_state.checker.check(token) {
+            ZeroRttCheckResult::Accept => ssl::SSLHelloRetryRequestAction::ssl_hello_retry_accept,
+            ZeroRttCheckResult::Fail => ssl::SSLHelloRetryRequestAction::ssl_hello_retry_fail,
+            ZeroRttCheckResult::Reject => {
+                ssl::SSLHelloRetryRequestAction::ssl_hello_retry_reject_0rtt
+            }
+            ZeroRttCheckResult::HelloRetryRequest(tok) => {
+                // Don't bother propagating errors from this, because it should be caught in
+                // testing.
+                assert!(tok.len() <= usize::try_from(retry_token_max).unwrap());
+                let slc = std::slice::from_raw_parts_mut(retry_token, tok.len());
+                slc.copy_from_slice(&tok);
+                *retry_token_len = c_uint::try_from(tok.len()).unwrap();
+                ssl::SSLHelloRetryRequestAction::ssl_hello_retry_request
+            }
+        }
+    }
+
+    /// Enable 0-RTT.  This shadows the function of the same name that can be accessed
+    /// via the Deref implementation on Server.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if the underlying NSS functions fail.
+    pub fn enable_0rtt(
+        &mut self,
+        anti_replay: &AntiReplay,
+        max_early_data: u32,
+        checker: Box<dyn ZeroRttChecker>,
+    ) -> Res<()> {
+        let mut check_state = Box::pin(ZeroRttCheckState::new(checker));
+        unsafe {
+            ssl::SSL_HelloRetryRequestCallback(
+                self.agent.fd,
+                Some(Self::hello_retry_cb),
+                as_c_void(&mut check_state),
+            )
+        }?;
+        unsafe { ssl::SSL_SetMaxEarlyDataSize(self.agent.fd, max_early_data) }?;
+        self.zero_rtt_check = Some(check_state);
+        self.agent.enable_0rtt()?;
+        anti_replay.config_socket(self.fd)?;
+        Ok(())
+    }
+
+    /// Send a session ticket to the client.
+    /// This adds |extra| application-specific content into that ticket.
+    /// The records that are sent are captured and returned.
+    ///
+    /// # Errors
+    ///
+    /// If NSS is unable to send a ticket, or if this agent is incorrectly configured.
+    pub fn send_ticket(&mut self, now: Instant, extra: &[u8]) -> Res<RecordList> {
+        self.agent.now.set(now)?;
+        let records = self.setup_raw()?;
+
+        unsafe {
+            ssl::SSL_SendSessionTicket(self.fd, extra.as_ptr(), c_uint::try_from(extra.len())?)
+        }?;
+
+        Ok(*Pin::into_inner(records))
+    }
+
+    /// Enable encrypted client hello (ECH).
+    ///
+    /// # Errors
+    ///
+    /// Fails when NSS cannot create a key pair.
+    pub fn enable_ech(
+        &mut self,
+        config: u8,
+        public_name: &str,
+        sk: &PrivateKey,
+        pk: &PublicKey,
+    ) -> Res<()> {
+        let cfg = ech::encode_config(config, public_name, pk)?;
+        qdebug!([self], "Enable ECH for a server: {}", hex_with_len(&cfg));
+        unsafe {
+            ech::SSL_SetServerEchConfigs(
+                self.agent.fd,
+                **pk,
+                **sk,
+                cfg.as_ptr(),
+                c_uint::try_from(cfg.len())?,
+            )?;
+        };
+        self.ech_config = cfg;
+        Ok(())
+    }
+}
+
+impl Deref for Server {
+    type Target = SecretAgent;
+    #[must_use]
+    fn deref(&self) -> &SecretAgent {
+        &self.agent
+    }
+}
+
+impl DerefMut for Server {
+    fn deref_mut(&mut self) -> &mut SecretAgent {
+        &mut self.agent
+    }
+}
+
+impl ::std::fmt::Display for Server {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "Server {:p}", self.agent.fd)
+    }
+}
+
+/// A generic container for Client or Server.
+#[derive(Debug)]
+pub enum Agent {
+    Client(crate::agent::Client),
+    Server(crate::agent::Server),
+}
+
+impl Deref for Agent {
+    type Target = SecretAgent;
+    #[must_use]
+    fn deref(&self) -> &SecretAgent {
+        match self {
+            Self::Client(c) => c,
+            Self::Server(s) => s,
+        }
+    }
+}
+
+impl DerefMut for Agent {
+    fn deref_mut(&mut self) -> &mut SecretAgent {
+        match self {
+            Self::Client(c) => c,
+            Self::Server(s) => s,
+        }
+    }
+}
+
+impl From<Client> for Agent {
+    #[must_use]
+    fn from(c: Client) -> Self {
+        Self::Client(c)
+    }
+}
+
+impl From<Server> for Agent {
+    #[must_use]
+    fn from(s: Server) -> Self {
+        Self::Server(s)
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/agentio.rs b/third_party/rust/neqo-crypto/src/agentio.rs
new file mode 100644
index 0000000000..2bcc540530
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/agentio.rs
@@ -0,0 +1,396 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    cmp::min,
+    convert::{TryFrom, TryInto},
+    fmt, mem,
+    ops::Deref,
+    os::raw::{c_uint, c_void},
+    pin::Pin,
+    ptr::{null, null_mut},
+    vec::Vec,
+};
+
+use neqo_common::{hex, hex_with_len, qtrace};
+
+use crate::{
+    constants::{ContentType, Epoch},
+    err::{nspr, Error, PR_SetError, Res},
+    prio, ssl,
+};
+
+// Alias common types.
+type PrFd = *mut prio::PRFileDesc;
+type PrStatus = prio::PRStatus::Type;
+const PR_SUCCESS: PrStatus = prio::PRStatus::PR_SUCCESS;
+const PR_FAILURE: PrStatus = prio::PRStatus::PR_FAILURE;
+
+/// Convert a pinned, boxed object into a void pointer.
+pub fn as_c_void<T: Unpin>(pin: &mut Pin<Box<T>>) -> *mut c_void {
+    (Pin::into_inner(pin.as_mut()) as *mut T).cast()
+}
+
+/// A slice of the output.
+#[derive(Default)]
+pub struct Record {
+    pub epoch: Epoch,
+    pub ct: ContentType,
+    pub data: Vec<u8>,
+}
+
+impl Record {
+    #[must_use]
+    pub fn new(epoch: Epoch, ct: ContentType, data: &[u8]) -> Self {
+        Self {
+            epoch,
+            ct,
+            data: data.to_vec(),
+        }
+    }
+
+    // Shoves this record into the socket, returns true if blocked.
+    pub(crate) fn write(self, fd: *mut ssl::PRFileDesc) -> Res<()> {
+        qtrace!("write {:?}", self);
+        unsafe {
+            ssl::SSL_RecordLayerData(
+                fd,
+                self.epoch,
+                ssl::SSLContentType::Type::from(self.ct),
+                self.data.as_ptr(),
+                c_uint::try_from(self.data.len())?,
+            )
+        }
+    }
+}
+
+impl fmt::Debug for Record {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "Record {:?}:{:?} {}",
+            self.epoch,
+            self.ct,
+            hex_with_len(&self.data[..])
+        )
+    }
+}
+
+#[derive(Debug, Default)]
+pub struct RecordList {
+    records: Vec<Record>,
+}
+
+impl RecordList {
+    fn append(&mut self, epoch: Epoch, ct: ContentType, data: &[u8]) {
+        self.records.push(Record::new(epoch, ct, data));
+    }
+
+    #[allow(clippy::unused_self)]
+    unsafe extern "C" fn ingest(
+        _fd: *mut ssl::PRFileDesc,
+        epoch: ssl::PRUint16,
+        ct: ssl::SSLContentType::Type,
+        data: *const ssl::PRUint8,
+        len: c_uint,
+        arg: *mut c_void,
+    ) -> ssl::SECStatus {
+        let records = arg.cast::<Self>().as_mut().unwrap();
+
+        let slice = std::slice::from_raw_parts(data, len as usize);
+        records.append(epoch, ContentType::try_from(ct).unwrap(), slice);
+        ssl::SECSuccess
+    }
+
+    /// Create a new record list.
+    pub(crate) fn setup(fd: *mut ssl::PRFileDesc) -> Res<Pin<Box<Self>>> {
+        let mut records = Box::pin(Self::default());
+        unsafe {
+            ssl::SSL_RecordLayerWriteCallback(fd, Some(Self::ingest), as_c_void(&mut records))
+        }?;
+        Ok(records)
+    }
+}
+
+impl Deref for RecordList {
+    type Target = Vec<Record>;
+    #[must_use]
+    fn deref(&self) -> &Vec<Record> {
+        &self.records
+    }
+}
+
+pub struct RecordListIter(std::vec::IntoIter<Record>);
+
+impl Iterator for RecordListIter {
+    type Item = Record;
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.next()
+    }
+}
+
+impl IntoIterator for RecordList {
+    type Item = Record;
+    type IntoIter = RecordListIter;
+    #[must_use]
+    fn into_iter(self) -> Self::IntoIter {
+        RecordListIter(self.records.into_iter())
+    }
+}
+
+pub struct AgentIoInputContext<'a> {
+    input: &'a mut AgentIoInput,
+}
+
+impl<'a> Drop for AgentIoInputContext<'a> {
+    fn drop(&mut self) {
+        self.input.reset();
+    }
+}
+
+#[derive(Debug)]
+struct AgentIoInput {
+    // input is data that is read by TLS.
+    input: *const u8,
+    // input_available is how much data is left for reading.
+    available: usize,
+}
+
+impl AgentIoInput {
+    fn wrap<'a: 'c, 'b: 'c, 'c>(&'a mut self, input: &'b [u8]) -> AgentIoInputContext<'c> {
+        assert!(self.input.is_null());
+        self.input = input.as_ptr();
+        self.available = input.len();
+        qtrace!("AgentIoInput wrap {:p}", self.input);
+        AgentIoInputContext { input: self }
+    }
+
+    // Take the data provided as input and provide it to the TLS stack.
+    fn read_input(&mut self, buf: *mut u8, count: usize) -> Res<usize> {
+        let amount = min(self.available, count);
+        if amount == 0 {
+            unsafe {
+                PR_SetError(nspr::PR_WOULD_BLOCK_ERROR, 0);
+            }
+            return Err(Error::NoDataAvailable);
+        }
+
+        let src = unsafe { std::slice::from_raw_parts(self.input, amount) };
+        qtrace!([self], "read {}", hex(src));
+        let dst = unsafe { std::slice::from_raw_parts_mut(buf, amount) };
+        dst.copy_from_slice(src);
+        self.input = self.input.wrapping_add(amount);
+        self.available -= amount;
+        Ok(amount)
+    }
+
+    fn reset(&mut self) {
+        qtrace!([self], "reset");
+        self.input = null();
+        self.available = 0;
+    }
+}
+
+impl ::std::fmt::Display for AgentIoInput {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "AgentIoInput {:p}", self.input)
+    }
+}
+
+#[derive(Debug)]
+pub struct AgentIo {
+    // input collects the input we might provide to TLS.
+    input: AgentIoInput,
+
+    // output contains data that is written by TLS.
+    output: Vec<u8>,
+}
+
+impl AgentIo {
+    pub fn new() -> Self {
+        Self {
+            input: AgentIoInput {
+                input: null(),
+                available: 0,
+            },
+            output: Vec::new(),
+        }
+    }
+
+    unsafe fn borrow(fd: &mut PrFd) -> &mut Self {
+        #[allow(clippy::cast_ptr_alignment)]
+        (**fd).secret.cast::<Self>().as_mut().unwrap()
+    }
+
+    pub fn wrap<'a: 'c, 'b: 'c, 'c>(&'a mut self, input: &'b [u8]) -> AgentIoInputContext<'c> {
+        assert_eq!(self.output.len(), 0);
+        self.input.wrap(input)
+    }
+
+    // Stage output from TLS into the output buffer.
+    fn save_output(&mut self, buf: *const u8, count: usize) {
+        let slice = unsafe { std::slice::from_raw_parts(buf, count) };
+        qtrace!([self], "save output {}", hex(slice));
+        self.output.extend_from_slice(slice);
+    }
+
+    pub fn take_output(&mut self) -> Vec<u8> {
+        qtrace!([self], "take output");
+        mem::take(&mut self.output)
+    }
+}
+
+impl ::std::fmt::Display for AgentIo {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "AgentIo")
+    }
+}
+
+unsafe extern "C" fn agent_close(fd: PrFd) -> PrStatus {
+    (*fd).secret = null_mut();
+    if let Some(dtor) = (*fd).dtor {
+        dtor(fd);
+    }
+    PR_SUCCESS
+}
+
+unsafe extern "C" fn agent_read(mut fd: PrFd, buf: *mut c_void, amount: prio::PRInt32) -> PrStatus {
+    let io = AgentIo::borrow(&mut fd);
+    if let Ok(a) = usize::try_from(amount) {
+        match io.input.read_input(buf.cast(), a) {
+            Ok(_) => PR_SUCCESS,
+            Err(_) => PR_FAILURE,
+        }
+    } else {
+        PR_FAILURE
+    }
+}
+
+unsafe extern "C" fn agent_recv(
+    mut fd: PrFd,
+    buf: *mut c_void,
+    amount: prio::PRInt32,
+    flags: prio::PRIntn,
+    _timeout: prio::PRIntervalTime,
+) -> prio::PRInt32 {
+    let io = AgentIo::borrow(&mut fd);
+    if flags != 0 {
+        return PR_FAILURE;
+    }
+    if let Ok(a) = usize::try_from(amount) {
+        match io.input.read_input(buf.cast(), a) {
+            Ok(v) => prio::PRInt32::try_from(v).unwrap_or(PR_FAILURE),
+            Err(_) => PR_FAILURE,
+        }
+    } else {
+        PR_FAILURE
+    }
+}
+
+unsafe extern "C" fn agent_write(
+    mut fd: PrFd,
+    buf: *const c_void,
+    amount: prio::PRInt32,
+) -> PrStatus {
+    let io = AgentIo::borrow(&mut fd);
+    if let Ok(a) = usize::try_from(amount) {
+        io.save_output(buf.cast(), a);
+        amount
+    } else {
+        PR_FAILURE
+    }
+}
+
+unsafe extern "C" fn agent_send(
+    mut fd: PrFd,
+    buf: *const c_void,
+    amount: prio::PRInt32,
+    flags: prio::PRIntn,
+    _timeout: prio::PRIntervalTime,
+) -> prio::PRInt32 {
+    let io = AgentIo::borrow(&mut fd);
+
+    if flags != 0 {
+        return PR_FAILURE;
+    }
+    if let Ok(a) = usize::try_from(amount) {
+        io.save_output(buf.cast(), a);
+        amount
+    } else {
+        PR_FAILURE
+    }
+}
+
+unsafe extern "C" fn agent_available(mut fd: PrFd) -> prio::PRInt32 {
+    let io = AgentIo::borrow(&mut fd);
+    io.input.available.try_into().unwrap_or(PR_FAILURE)
+}
+
+unsafe extern "C" fn agent_available64(mut fd: PrFd) -> prio::PRInt64 {
+    let io = AgentIo::borrow(&mut fd);
+    io.input
+        .available
+        .try_into()
+        .unwrap_or_else(|_| PR_FAILURE.into())
+}
+
+#[allow(clippy::cast_possible_truncation)]
+unsafe extern "C" fn agent_getname(_fd: PrFd, addr: *mut prio::PRNetAddr) -> PrStatus {
+    let a = addr.as_mut().unwrap();
+    // Cast is safe because prio::PR_AF_INET is 2
+    a.inet.family = prio::PR_AF_INET as prio::PRUint16;
+    a.inet.port = 0;
+    a.inet.ip = 0;
+    PR_SUCCESS
+}
+
+unsafe extern "C" fn agent_getsockopt(_fd: PrFd, opt: *mut prio::PRSocketOptionData) -> PrStatus {
+    let o = opt.as_mut().unwrap();
+    if o.option == prio::PRSockOption::PR_SockOpt_Nonblocking {
+        o.value.non_blocking = 1;
+        return PR_SUCCESS;
+    }
+    PR_FAILURE
+}
+
+pub const METHODS: &prio::PRIOMethods = &prio::PRIOMethods {
+    file_type: prio::PRDescType::PR_DESC_LAYERED,
+    close: Some(agent_close),
+    read: Some(agent_read),
+    write: Some(agent_write),
+    available: Some(agent_available),
+    available64: Some(agent_available64),
+    fsync: None,
+    seek: None,
+    seek64: None,
+    fileInfo: None,
+    fileInfo64: None,
+    writev: None,
+    connect: None,
+    accept: None,
+    bind: None,
+    listen: None,
+    shutdown: None,
+    recv: Some(agent_recv),
+    send: Some(agent_send),
+    recvfrom: None,
+    sendto: None,
+    poll: None,
+    acceptread: None,
+    transmitfile: None,
+    getsockname: Some(agent_getname),
+    getpeername: Some(agent_getname),
+    reserved_fn_6: None,
+    reserved_fn_5: None,
+    getsocketoption: Some(agent_getsockopt),
+    setsocketoption: None,
+    sendfile: None,
+    connectcontinue: None,
+    reserved_fn_3: None,
+    reserved_fn_2: None,
+    reserved_fn_1: None,
+    reserved_fn_0: None,
+};
diff --git a/third_party/rust/neqo-crypto/src/auth.rs b/third_party/rust/neqo-crypto/src/auth.rs
new file mode 100644
index 0000000000..2932cdf2eb
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/auth.rs
@@ -0,0 +1,108 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use crate::err::{mozpkix, sec, ssl, PRErrorCode};
+
+/// The outcome of authentication.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum AuthenticationStatus {
+    Ok,
+    CaInvalid,
+    CaNotV3,
+    CertAlgorithmDisabled,
+    CertExpired,
+    CertInvalidTime,
+    CertIsCa,
+    CertKeyUsage,
+    CertMitm,
+    CertNotYetValid,
+    CertRevoked,
+    CertSelfSigned,
+    CertSubjectInvalid,
+    CertUntrusted,
+    CertWeakKey,
+    IssuerEmptyName,
+    IssuerExpired,
+    IssuerNotYetValid,
+    IssuerUnknown,
+    IssuerUntrusted,
+    PolicyRejection,
+    Unknown,
+}
+
+impl From<AuthenticationStatus> for PRErrorCode {
+    #[must_use]
+    fn from(v: AuthenticationStatus) -> Self {
+        match v {
+            AuthenticationStatus::Ok => 0,
+            AuthenticationStatus::CaInvalid => sec::SEC_ERROR_CA_CERT_INVALID,
+            AuthenticationStatus::CaNotV3 => mozpkix::MOZILLA_PKIX_ERROR_V1_CERT_USED_AS_CA,
+            AuthenticationStatus::CertAlgorithmDisabled => {
+                sec::SEC_ERROR_CERT_SIGNATURE_ALGORITHM_DISABLED
+            }
+            AuthenticationStatus::CertExpired => sec::SEC_ERROR_EXPIRED_CERTIFICATE,
+            AuthenticationStatus::CertInvalidTime => sec::SEC_ERROR_INVALID_TIME,
+            AuthenticationStatus::CertIsCa => {
+                mozpkix::MOZILLA_PKIX_ERROR_CA_CERT_USED_AS_END_ENTITY
+            }
+            AuthenticationStatus::CertKeyUsage => sec::SEC_ERROR_INADEQUATE_KEY_USAGE,
+            AuthenticationStatus::CertMitm => mozpkix::MOZILLA_PKIX_ERROR_MITM_DETECTED,
+            AuthenticationStatus::CertNotYetValid => {
+                mozpkix::MOZILLA_PKIX_ERROR_NOT_YET_VALID_CERTIFICATE
+            }
+            AuthenticationStatus::CertRevoked => sec::SEC_ERROR_REVOKED_CERTIFICATE,
+            AuthenticationStatus::CertSelfSigned => mozpkix::MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT,
+            AuthenticationStatus::CertSubjectInvalid => ssl::SSL_ERROR_BAD_CERT_DOMAIN,
+            AuthenticationStatus::CertUntrusted => sec::SEC_ERROR_UNTRUSTED_CERT,
+            AuthenticationStatus::CertWeakKey => mozpkix::MOZILLA_PKIX_ERROR_INADEQUATE_KEY_SIZE,
+            AuthenticationStatus::IssuerEmptyName => mozpkix::MOZILLA_PKIX_ERROR_EMPTY_ISSUER_NAME,
+            AuthenticationStatus::IssuerExpired => sec::SEC_ERROR_EXPIRED_ISSUER_CERTIFICATE,
+            AuthenticationStatus::IssuerNotYetValid => {
+                mozpkix::MOZILLA_PKIX_ERROR_NOT_YET_VALID_ISSUER_CERTIFICATE
+            }
+            AuthenticationStatus::IssuerUnknown => sec::SEC_ERROR_UNKNOWN_ISSUER,
+            AuthenticationStatus::IssuerUntrusted => sec::SEC_ERROR_UNTRUSTED_ISSUER,
+            AuthenticationStatus::PolicyRejection => {
+                mozpkix::MOZILLA_PKIX_ERROR_ADDITIONAL_POLICY_CONSTRAINT_FAILED
+            }
+            AuthenticationStatus::Unknown => sec::SEC_ERROR_LIBRARY_FAILURE,
+        }
+    }
+}
+
+// Note that this mapping should be removed after gecko eventually learns how to
+// map into the enumerated type.
+impl From<PRErrorCode> for AuthenticationStatus {
+    #[must_use]
+    fn from(v: PRErrorCode) -> Self {
+        match v {
+            0 => Self::Ok,
+            sec::SEC_ERROR_CA_CERT_INVALID => Self::CaInvalid,
+            mozpkix::MOZILLA_PKIX_ERROR_V1_CERT_USED_AS_CA => Self::CaNotV3,
+            sec::SEC_ERROR_CERT_SIGNATURE_ALGORITHM_DISABLED => Self::CertAlgorithmDisabled,
+            sec::SEC_ERROR_EXPIRED_CERTIFICATE => Self::CertExpired,
+            sec::SEC_ERROR_INVALID_TIME => Self::CertInvalidTime,
+            mozpkix::MOZILLA_PKIX_ERROR_CA_CERT_USED_AS_END_ENTITY => Self::CertIsCa,
+            sec::SEC_ERROR_INADEQUATE_KEY_USAGE => Self::CertKeyUsage,
+            mozpkix::MOZILLA_PKIX_ERROR_MITM_DETECTED => Self::CertMitm,
+            mozpkix::MOZILLA_PKIX_ERROR_NOT_YET_VALID_CERTIFICATE => Self::CertNotYetValid,
+            sec::SEC_ERROR_REVOKED_CERTIFICATE => Self::CertRevoked,
+            mozpkix::MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT => Self::CertSelfSigned,
+            ssl::SSL_ERROR_BAD_CERT_DOMAIN => Self::CertSubjectInvalid,
+            sec::SEC_ERROR_UNTRUSTED_CERT => Self::CertUntrusted,
+            mozpkix::MOZILLA_PKIX_ERROR_INADEQUATE_KEY_SIZE => Self::CertWeakKey,
+            mozpkix::MOZILLA_PKIX_ERROR_EMPTY_ISSUER_NAME => Self::IssuerEmptyName,
+            sec::SEC_ERROR_EXPIRED_ISSUER_CERTIFICATE => Self::IssuerExpired,
+            mozpkix::MOZILLA_PKIX_ERROR_NOT_YET_VALID_ISSUER_CERTIFICATE => Self::IssuerNotYetValid,
+            sec::SEC_ERROR_UNKNOWN_ISSUER => Self::IssuerUnknown,
+            sec::SEC_ERROR_UNTRUSTED_ISSUER => Self::IssuerUntrusted,
+            mozpkix::MOZILLA_PKIX_ERROR_ADDITIONAL_POLICY_CONSTRAINT_FAILED => {
+                Self::PolicyRejection
+            }
+            _ => Self::Unknown,
+        }
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/cert.rs b/third_party/rust/neqo-crypto/src/cert.rs
new file mode 100644
index 0000000000..64e63ec71a
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/cert.rs
@@ -0,0 +1,120 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    convert::TryFrom,
+    ptr::{addr_of, NonNull},
+    slice,
+};
+
+use neqo_common::qerror;
+
+use crate::{
+    err::secstatus_to_res,
+    p11::{CERTCertListNode, CERT_GetCertificateDer, CertList, Item, SECItem, SECItemArray},
+    ssl::{
+        PRFileDesc, SSL_PeerCertificateChain, SSL_PeerSignedCertTimestamps,
+        SSL_PeerStapledOCSPResponses,
+    },
+};
+
+pub struct CertificateInfo {
+    certs: CertList,
+    cursor: *const CERTCertListNode,
+    /// stapled_ocsp_responses and signed_cert_timestamp are properties
+    /// associated with each of the certificates. Right now, NSS only
+    /// reports the value for the end-entity certificate (the first).
+    stapled_ocsp_responses: Option<Vec<Vec<u8>>>,
+    signed_cert_timestamp: Option<Vec<u8>>,
+}
+
+fn peer_certificate_chain(fd: *mut PRFileDesc) -> Option<(CertList, *const CERTCertListNode)> {
+    let chain = unsafe { SSL_PeerCertificateChain(fd) };
+    CertList::from_ptr(chain.cast()).ok().map(|certs| {
+        let cursor = CertificateInfo::head(&certs);
+        (certs, cursor)
+    })
+}
+
+// As explained in rfc6961, an OCSPResponseList can have at most
+// 2^24 items. Casting its length is therefore safe even on 32 bits targets.
+fn stapled_ocsp_responses(fd: *mut PRFileDesc) -> Option<Vec<Vec<u8>>> {
+    let ocsp_nss = unsafe { SSL_PeerStapledOCSPResponses(fd) };
+    match NonNull::new(ocsp_nss as *mut SECItemArray) {
+        Some(ocsp_ptr) => {
+            let mut ocsp_helper: Vec<Vec<u8>> = Vec::new();
+            let Ok(len) = isize::try_from(unsafe { ocsp_ptr.as_ref().len }) else {
+                qerror!([format!("{fd:p}")], "Received illegal OSCP length");
+                return None;
+            };
+            for idx in 0..len {
+                let itemp: *const SECItem = unsafe { ocsp_ptr.as_ref().items.offset(idx).cast() };
+                let item = unsafe { slice::from_raw_parts((*itemp).data, (*itemp).len as usize) };
+                ocsp_helper.push(item.to_owned());
+            }
+            Some(ocsp_helper)
+        }
+        None => None,
+    }
+}
+
+fn signed_cert_timestamp(fd: *mut PRFileDesc) -> Option<Vec<u8>> {
+    let sct_nss = unsafe { SSL_PeerSignedCertTimestamps(fd) };
+    match NonNull::new(sct_nss as *mut SECItem) {
+        Some(sct_ptr) => {
+            if unsafe { sct_ptr.as_ref().len == 0 || sct_ptr.as_ref().data.is_null() } {
+                Some(Vec::new())
+            } else {
+                let sct_slice = unsafe {
+                    slice::from_raw_parts(sct_ptr.as_ref().data, sct_ptr.as_ref().len as usize)
+                };
+                Some(sct_slice.to_owned())
+            }
+        }
+        None => None,
+    }
+}
+
+impl CertificateInfo {
+    pub(crate) fn new(fd: *mut PRFileDesc) -> Option<Self> {
+        peer_certificate_chain(fd).map(|(certs, cursor)| Self {
+            certs,
+            cursor,
+            stapled_ocsp_responses: stapled_ocsp_responses(fd),
+            signed_cert_timestamp: signed_cert_timestamp(fd),
+        })
+    }
+
+    fn head(certs: &CertList) -> *const CERTCertListNode {
+        // Three stars: one for the reference, one for the wrapper, one to deference the pointer.
+        unsafe { addr_of!((***certs).list).cast() }
+    }
+}
+
+impl<'a> Iterator for &'a mut CertificateInfo {
+    type Item = &'a [u8];
+    fn next(&mut self) -> Option<&'a [u8]> {
+        self.cursor = unsafe { *self.cursor }.links.next.cast();
+        if self.cursor == CertificateInfo::head(&self.certs) {
+            return None;
+        }
+        let mut item = Item::make_empty();
+        let cert = unsafe { *self.cursor }.cert;
+        secstatus_to_res(unsafe { CERT_GetCertificateDer(cert, &mut item) })
+            .expect("getting DER from certificate should work");
+        Some(unsafe { std::slice::from_raw_parts(item.data, item.len as usize) })
+    }
+}
+
+impl CertificateInfo {
+    pub fn stapled_ocsp_responses(&mut self) -> &Option<Vec<Vec<u8>>> {
+        &self.stapled_ocsp_responses
+    }
+
+    pub fn signed_cert_timestamp(&mut self) -> &Option<Vec<u8>> {
+        &self.signed_cert_timestamp
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/constants.rs b/third_party/rust/neqo-crypto/src/constants.rs
new file mode 100644
index 0000000000..76db972290
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/constants.rs
@@ -0,0 +1,146 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(dead_code)]
+
+use crate::ssl;
+
+// Ideally all of these would be enums, but size matters and we need to allow
+// for values outside of those that are defined here.
+
+pub type Alert = u8;
+
+pub type Epoch = u16;
+// TLS doesn't really have an "initial" concept that maps to QUIC so directly,
+// but this should be clear enough.
+pub const TLS_EPOCH_INITIAL: Epoch = 0_u16;
+pub const TLS_EPOCH_ZERO_RTT: Epoch = 1_u16;
+pub const TLS_EPOCH_HANDSHAKE: Epoch = 2_u16;
+// Also, we don't use TLS epochs > 3.
+pub const TLS_EPOCH_APPLICATION_DATA: Epoch = 3_u16;
+
+/// Rather than defining a type alias and a bunch of constants, which leads to a ton of repetition,
+/// use this macro.
+macro_rules! remap_enum {
+    { $t:ident: $s:ty { $( $n:ident = $v:path ),+ $(,)? } } => {
+        pub type $t = $s;
+        $( pub const $n: $t = $v as $t; )+
+    };
+    { $t:ident: $s:ty => $e:ident { $( $n:ident = $v:ident ),+ $(,)? } } => {
+        remap_enum!{ $t: $s { $( $n = $e::$v ),+ } }
+    };
+    { $t:ident: $s:ty => $p:ident::$e:ident { $( $n:ident = $v:ident ),+ $(,)? } } => {
+        remap_enum!{ $t: $s { $( $n = $p::$e::$v ),+ } }
+    };
+}
+
+remap_enum! {
+    Version: u16 => ssl {
+        TLS_VERSION_1_2 = SSL_LIBRARY_VERSION_TLS_1_2,
+        TLS_VERSION_1_3 = SSL_LIBRARY_VERSION_TLS_1_3,
+    }
+}
+
+mod ciphers {
+    include!(concat!(env!("OUT_DIR"), "/nss_ciphers.rs"));
+}
+
+remap_enum! {
+    Cipher: u16 => ciphers {
+        TLS_AES_128_GCM_SHA256 = TLS_AES_128_GCM_SHA256,
+        TLS_AES_256_GCM_SHA384 = TLS_AES_256_GCM_SHA384,
+        TLS_CHACHA20_POLY1305_SHA256 = TLS_CHACHA20_POLY1305_SHA256,
+    }
+}
+
+remap_enum! {
+    Group: u16 => ssl::SSLNamedGroup {
+        TLS_GRP_EC_SECP256R1 = ssl_grp_ec_secp256r1,
+        TLS_GRP_EC_SECP384R1 = ssl_grp_ec_secp384r1,
+        TLS_GRP_EC_SECP521R1 = ssl_grp_ec_secp521r1,
+        TLS_GRP_EC_X25519 = ssl_grp_ec_curve25519,
+        TLS_GRP_KEM_XYBER768D00 = ssl_grp_kem_xyber768d00,
+    }
+}
+
+remap_enum! {
+    HandshakeMessage: u8 => ssl::SSLHandshakeType {
+        TLS_HS_HELLO_REQUEST = ssl_hs_hello_request,
+        TLS_HS_CLIENT_HELLO = ssl_hs_client_hello,
+        TLS_HS_SERVER_HELLO = ssl_hs_server_hello,
+        TLS_HS_HELLO_VERIFY_REQUEST = ssl_hs_hello_verify_request,
+        TLS_HS_NEW_SESSION_TICKET = ssl_hs_new_session_ticket,
+        TLS_HS_END_OF_EARLY_DATA = ssl_hs_end_of_early_data,
+        TLS_HS_HELLO_RETRY_REQUEST = ssl_hs_hello_retry_request,
+        TLS_HS_ENCRYPTED_EXTENSIONS = ssl_hs_encrypted_extensions,
+        TLS_HS_CERTIFICATE = ssl_hs_certificate,
+        TLS_HS_SERVER_KEY_EXCHANGE = ssl_hs_server_key_exchange,
+        TLS_HS_CERTIFICATE_REQUEST = ssl_hs_certificate_request,
+        TLS_HS_SERVER_HELLO_DONE = ssl_hs_server_hello_done,
+        TLS_HS_CERTIFICATE_VERIFY = ssl_hs_certificate_verify,
+        TLS_HS_CLIENT_KEY_EXCHANGE = ssl_hs_client_key_exchange,
+        TLS_HS_FINISHED = ssl_hs_finished,
+        TLS_HS_CERT_STATUS = ssl_hs_certificate_status,
+        TLS_HS_KEY_UDPATE = ssl_hs_key_update,
+    }
+}
+
+remap_enum! {
+    ContentType: u8 => ssl::SSLContentType {
+        TLS_CT_CHANGE_CIPHER_SPEC = ssl_ct_change_cipher_spec,
+        TLS_CT_ALERT = ssl_ct_alert,
+        TLS_CT_HANDSHAKE = ssl_ct_handshake,
+        TLS_CT_APPLICATION_DATA = ssl_ct_application_data,
+        TLS_CT_ACK = ssl_ct_ack,
+    }
+}
+
+remap_enum! {
+    Extension: u16 => ssl::SSLExtensionType {
+        TLS_EXT_SERVER_NAME = ssl_server_name_xtn,
+        TLS_EXT_CERT_STATUS = ssl_cert_status_xtn,
+        TLS_EXT_GROUPS = ssl_supported_groups_xtn,
+        TLS_EXT_EC_POINT_FORMATS = ssl_ec_point_formats_xtn,
+        TLS_EXT_SIG_SCHEMES = ssl_signature_algorithms_xtn,
+        TLS_EXT_USE_SRTP = ssl_use_srtp_xtn,
+        TLS_EXT_ALPN = ssl_app_layer_protocol_xtn,
+        TLS_EXT_SCT = ssl_signed_cert_timestamp_xtn,
+        TLS_EXT_PADDING = ssl_padding_xtn,
+        TLS_EXT_EMS = ssl_extended_master_secret_xtn,
+        TLS_EXT_RECORD_SIZE = ssl_record_size_limit_xtn,
+        TLS_EXT_SESSION_TICKET = ssl_session_ticket_xtn,
+        TLS_EXT_PSK = ssl_tls13_pre_shared_key_xtn,
+        TLS_EXT_EARLY_DATA = ssl_tls13_early_data_xtn,
+        TLS_EXT_VERSIONS = ssl_tls13_supported_versions_xtn,
+        TLS_EXT_COOKIE = ssl_tls13_cookie_xtn,
+        TLS_EXT_PSK_MODES = ssl_tls13_psk_key_exchange_modes_xtn,
+        TLS_EXT_CA = ssl_tls13_certificate_authorities_xtn,
+        TLS_EXT_POST_HS_AUTH = ssl_tls13_post_handshake_auth_xtn,
+        TLS_EXT_CERT_SIG_SCHEMES = ssl_signature_algorithms_cert_xtn,
+        TLS_EXT_KEY_SHARE = ssl_tls13_key_share_xtn,
+        TLS_EXT_RENEGOTIATION_INFO = ssl_renegotiation_info_xtn,
+    }
+}
+
+remap_enum! {
+    SignatureScheme: u16 => ssl::SSLSignatureScheme {
+        TLS_SIG_NONE = ssl_sig_none,
+        TLS_SIG_RSA_PKCS1_SHA256 = ssl_sig_rsa_pkcs1_sha256,
+        TLS_SIG_RSA_PKCS1_SHA384 = ssl_sig_rsa_pkcs1_sha384,
+        TLS_SIG_RSA_PKCS1_SHA512 = ssl_sig_rsa_pkcs1_sha512,
+        TLS_SIG_ECDSA_SECP256R1_SHA256 = ssl_sig_ecdsa_secp256r1_sha256,
+        TLS_SIG_ECDSA_SECP384R1_SHA384 = ssl_sig_ecdsa_secp384r1_sha384,
+        TLS_SIG_ECDSA_SECP512R1_SHA512 = ssl_sig_ecdsa_secp521r1_sha512,
+        TLS_SIG_RSA_PSS_RSAE_SHA256 = ssl_sig_rsa_pss_rsae_sha256,
+        TLS_SIG_RSA_PSS_RSAE_SHA384 = ssl_sig_rsa_pss_rsae_sha384,
+        TLS_SIG_RSA_PSS_RSAE_SHA512 = ssl_sig_rsa_pss_rsae_sha512,
+        TLS_SIG_ED25519 = ssl_sig_ed25519,
+        TLS_SIG_ED448 = ssl_sig_ed448,
+        TLS_SIG_RSA_PSS_PSS_SHA256 = ssl_sig_rsa_pss_pss_sha256,
+        TLS_SIG_RSA_PSS_PSS_SHA384 = ssl_sig_rsa_pss_pss_sha384,
+        TLS_SIG_RSA_PSS_PSS_SHA512 = ssl_sig_rsa_pss_pss_sha512,
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/ech.rs b/third_party/rust/neqo-crypto/src/ech.rs
new file mode 100644
index 0000000000..1f54c4592e
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/ech.rs
@@ -0,0 +1,204 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    convert::TryFrom,
+    ffi::CString,
+    os::raw::{c_char, c_uint},
+    ptr::{addr_of_mut, null_mut},
+};
+
+use neqo_common::qtrace;
+
+use crate::{
+    err::{ssl::SSL_ERROR_ECH_RETRY_WITH_ECH, Error, Res},
+    experimental_api,
+    p11::{
+        self, Item, PrivateKey, PublicKey, SECITEM_FreeItem, SECItem, SECKEYPrivateKey,
+        SECKEYPublicKey, Slot,
+    },
+    ssl::{PRBool, PRFileDesc},
+};
+pub use crate::{
+    p11::{HpkeAeadId as AeadId, HpkeKdfId as KdfId, HpkeKemId as KemId},
+    ssl::HpkeSymmetricSuite as SymmetricSuite,
+};
+
+experimental_api!(SSL_EnableTls13GreaseEch(
+    fd: *mut PRFileDesc,
+    enabled: PRBool,
+));
+
+experimental_api!(SSL_GetEchRetryConfigs(
+    fd: *mut PRFileDesc,
+    config: *mut SECItem,
+));
+
+experimental_api!(SSL_SetClientEchConfigs(
+    fd: *mut PRFileDesc,
+    config_list: *const u8,
+    config_list_len: c_uint,
+));
+
+experimental_api!(SSL_SetServerEchConfigs(
+    fd: *mut PRFileDesc,
+    pk: *const SECKEYPublicKey,
+    sk: *const SECKEYPrivateKey,
+    record: *const u8,
+    record_len: c_uint,
+));
+
+experimental_api!(SSL_EncodeEchConfigId(
+    config_id: u8,
+    public_name: *const c_char,
+    max_name_len: c_uint,
+    kem_id: KemId::Type,
+    pk: *const SECKEYPublicKey,
+    hpke_suites: *const SymmetricSuite,
+    hpke_suite_count: c_uint,
+    out: *mut u8,
+    out_len: *mut c_uint,
+    max_len: c_uint,
+));
+
+/// Convert any result that contains an ECH error into a result with an `EchRetry`.
+pub fn convert_ech_error(fd: *mut PRFileDesc, err: Error) -> Error {
+    if let Error::NssError {
+        code: SSL_ERROR_ECH_RETRY_WITH_ECH,
+        ..
+    } = &err
+    {
+        let mut item = Item::make_empty();
+        if unsafe { SSL_GetEchRetryConfigs(fd, &mut item).is_err() } {
+            return Error::InternalError;
+        }
+        let buf = unsafe {
+            let slc = std::slice::from_raw_parts(item.data, usize::try_from(item.len).unwrap());
+            let buf = Vec::from(slc);
+            SECITEM_FreeItem(&mut item, PRBool::from(false));
+            buf
+        };
+        Error::EchRetry(buf)
+    } else {
+        err
+    }
+}
+
+/// Generate a key pair for encrypted client hello (ECH).
+///
+/// # Errors
+///
+/// When NSS fails to generate a key pair or when the KEM is not supported.
+///
+/// # Panics
+///
+/// When underlying types aren't large enough to hold keys.  So never.
+pub fn generate_keys() -> Res<(PrivateKey, PublicKey)> {
+    let slot = Slot::internal()?;
+
+    let oid_data = unsafe { p11::SECOID_FindOIDByTag(p11::SECOidTag::SEC_OID_CURVE25519) };
+    let oid = unsafe { oid_data.as_ref() }.ok_or(Error::InternalError)?;
+    let oid_slc =
+        unsafe { std::slice::from_raw_parts(oid.oid.data, usize::try_from(oid.oid.len).unwrap()) };
+    let mut params: Vec<u8> = Vec::with_capacity(oid_slc.len() + 2);
+    params.push(u8::try_from(p11::SEC_ASN1_OBJECT_ID).unwrap());
+    params.push(u8::try_from(oid.oid.len).unwrap());
+    params.extend_from_slice(oid_slc);
+
+    let mut public_ptr: *mut SECKEYPublicKey = null_mut();
+    let mut param_item = Item::wrap(&params);
+
+    // If we have tracing on, try to ensure that key data can be read.
+    let insensitive_secret_ptr = if log::log_enabled!(log::Level::Trace) {
+        #[allow(clippy::useless_conversion)] // TODO: Remove when we bump the MSRV to 1.74.0.
+        unsafe {
+            p11::PK11_GenerateKeyPairWithOpFlags(
+                *slot,
+                p11::CK_MECHANISM_TYPE::from(p11::CKM_EC_KEY_PAIR_GEN),
+                addr_of_mut!(param_item).cast(),
+                &mut public_ptr,
+                p11::PK11_ATTR_SESSION | p11::PK11_ATTR_INSENSITIVE | p11::PK11_ATTR_PUBLIC,
+                p11::CK_FLAGS::from(p11::CKF_DERIVE),
+                p11::CK_FLAGS::from(p11::CKF_DERIVE),
+                null_mut(),
+            )
+        }
+    } else {
+        null_mut()
+    };
+    assert_eq!(insensitive_secret_ptr.is_null(), public_ptr.is_null());
+    let secret_ptr = if insensitive_secret_ptr.is_null() {
+        #[allow(clippy::useless_conversion)] // TODO: Remove when we bump the MSRV to 1.74.0.
+        unsafe {
+            p11::PK11_GenerateKeyPairWithOpFlags(
+                *slot,
+                p11::CK_MECHANISM_TYPE::from(p11::CKM_EC_KEY_PAIR_GEN),
+                addr_of_mut!(param_item).cast(),
+                &mut public_ptr,
+                p11::PK11_ATTR_SESSION | p11::PK11_ATTR_SENSITIVE | p11::PK11_ATTR_PRIVATE,
+                p11::CK_FLAGS::from(p11::CKF_DERIVE),
+                p11::CK_FLAGS::from(p11::CKF_DERIVE),
+                null_mut(),
+            )
+        }
+    } else {
+        insensitive_secret_ptr
+    };
+    assert_eq!(secret_ptr.is_null(), public_ptr.is_null());
+    let sk = PrivateKey::from_ptr(secret_ptr)?;
+    let pk = PublicKey::from_ptr(public_ptr)?;
+    qtrace!("Generated key pair: sk={:?} pk={:?}", sk, pk);
+    Ok((sk, pk))
+}
+
+/// Encode a configuration for encrypted client hello (ECH).
+///
+/// # Errors
+///
+/// When NSS fails to generate a valid configuration encoding (i.e., unlikely).
+pub fn encode_config(config: u8, public_name: &str, pk: &PublicKey) -> Res<Vec<u8>> {
+    // A sensible fixed value for the maximum length of a name.
+    const MAX_NAME_LEN: c_uint = 64;
+    // Enable a selection of suites.
+    // NSS supports SHA-512 as well, which could be added here.
+    const SUITES: &[SymmetricSuite] = &[
+        SymmetricSuite {
+            kdfId: KdfId::HpkeKdfHkdfSha256,
+            aeadId: AeadId::HpkeAeadAes128Gcm,
+        },
+        SymmetricSuite {
+            kdfId: KdfId::HpkeKdfHkdfSha256,
+            aeadId: AeadId::HpkeAeadChaCha20Poly1305,
+        },
+        SymmetricSuite {
+            kdfId: KdfId::HpkeKdfHkdfSha384,
+            aeadId: AeadId::HpkeAeadAes128Gcm,
+        },
+        SymmetricSuite {
+            kdfId: KdfId::HpkeKdfHkdfSha384,
+            aeadId: AeadId::HpkeAeadChaCha20Poly1305,
+        },
+    ];
+
+    let name = CString::new(public_name)?;
+    let mut encoded = [0; 1024];
+    let mut encoded_len = 0;
+    unsafe {
+        SSL_EncodeEchConfigId(
+            config,
+            name.as_ptr(),
+            MAX_NAME_LEN,
+            KemId::HpkeDhKemX25519Sha256,
+            **pk,
+            SUITES.as_ptr(),
+            c_uint::try_from(SUITES.len())?,
+            encoded.as_mut_ptr(),
+            &mut encoded_len,
+            c_uint::try_from(encoded.len())?,
+        )?;
+    }
+    Ok(Vec::from(&encoded[..usize::try_from(encoded_len)?]))
+}
diff --git a/third_party/rust/neqo-crypto/src/err.rs b/third_party/rust/neqo-crypto/src/err.rs
new file mode 100644
index 0000000000..187303d2a9
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/err.rs
@@ -0,0 +1,214 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(dead_code)]
+#![allow(clippy::upper_case_acronyms)]
+
+use std::{os::raw::c_char, str::Utf8Error};
+
+use crate::ssl::{SECStatus, SECSuccess};
+
+include!(concat!(env!("OUT_DIR"), "/nspr_error.rs"));
+mod codes {
+    #![allow(non_snake_case)]
+    include!(concat!(env!("OUT_DIR"), "/nss_secerr.rs"));
+    include!(concat!(env!("OUT_DIR"), "/nss_sslerr.rs"));
+    include!(concat!(env!("OUT_DIR"), "/mozpkix.rs"));
+}
+pub use codes::{mozilla_pkix_ErrorCode as mozpkix, SECErrorCodes as sec, SSLErrorCodes as ssl};
+pub mod nspr {
+    include!(concat!(env!("OUT_DIR"), "/nspr_err.rs"));
+}
+
+pub type Res<T> = Result<T, Error>;
+
+#[derive(Clone, Debug, PartialEq, PartialOrd, Ord, Eq)]
+pub enum Error {
+    AeadError,
+    CertificateLoading,
+    CipherInitFailure,
+    CreateSslSocket,
+    EchRetry(Vec<u8>),
+    HkdfError,
+    InternalError,
+    IntegerOverflow,
+    InvalidEpoch,
+    MixedHandshakeMethod,
+    NoDataAvailable,
+    NssError {
+        name: String,
+        code: PRErrorCode,
+        desc: String,
+    },
+    OverrunError,
+    SelfEncryptFailure,
+    StringError,
+    TimeTravelError,
+    UnsupportedCipher,
+    UnsupportedVersion,
+}
+
+impl Error {
+    pub(crate) fn last_nss_error() -> Self {
+        Self::from(unsafe { PR_GetError() })
+    }
+}
+
+impl std::error::Error for Error {
+    #[must_use]
+    fn cause(&self) -> Option<&dyn std::error::Error> {
+        None
+    }
+    #[must_use]
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        None
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "Error: {self:?}")
+    }
+}
+
+impl From<std::num::TryFromIntError> for Error {
+    #[must_use]
+    fn from(_: std::num::TryFromIntError) -> Self {
+        Self::IntegerOverflow
+    }
+}
+impl From<std::ffi::NulError> for Error {
+    #[must_use]
+    fn from(_: std::ffi::NulError) -> Self {
+        Self::InternalError
+    }
+}
+impl From<Utf8Error> for Error {
+    fn from(_: Utf8Error) -> Self {
+        Self::StringError
+    }
+}
+impl From<PRErrorCode> for Error {
+    fn from(code: PRErrorCode) -> Self {
+        let name = wrap_str_fn(|| unsafe { PR_ErrorToName(code) }, "UNKNOWN_ERROR");
+        let desc = wrap_str_fn(
+            || unsafe { PR_ErrorToString(code, PR_LANGUAGE_I_DEFAULT) },
+            "...",
+        );
+        Self::NssError { name, code, desc }
+    }
+}
+
+use std::ffi::CStr;
+
+fn wrap_str_fn<F>(f: F, dflt: &str) -> String
+where
+    F: FnOnce() -> *const c_char,
+{
+    unsafe {
+        let p = f();
+        if p.is_null() {
+            return dflt.to_string();
+        }
+        CStr::from_ptr(p).to_string_lossy().into_owned()
+    }
+}
+
+pub fn secstatus_to_res(rv: SECStatus) -> Res<()> {
+    if rv == SECSuccess {
+        Ok(())
+    } else {
+        Err(Error::last_nss_error())
+    }
+}
+
+pub fn is_blocked(result: &Res<()>) -> bool {
+    match result {
+        Err(Error::NssError { code, .. }) => *code == nspr::PR_WOULD_BLOCK_ERROR,
+        _ => false,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use test_fixture::fixture_init;
+
+    use crate::{
+        err::{self, is_blocked, secstatus_to_res, Error, PRErrorCode, PR_SetError},
+        ssl::{SECFailure, SECSuccess},
+    };
+
+    fn set_error_code(code: PRErrorCode) {
+        // This code doesn't work without initializing NSS first.
+        fixture_init();
+        unsafe {
+            PR_SetError(code, 0);
+        }
+    }
+
+    #[test]
+    fn error_code() {
+        fixture_init();
+        assert_eq!(15 - 0x3000, err::ssl::SSL_ERROR_BAD_MAC_READ);
+        assert_eq!(166 - 0x2000, err::sec::SEC_ERROR_LIBPKIX_INTERNAL);
+        assert_eq!(-5998, err::nspr::PR_WOULD_BLOCK_ERROR);
+    }
+
+    #[test]
+    fn is_ok() {
+        assert!(secstatus_to_res(SECSuccess).is_ok());
+    }
+
+    #[test]
+    fn is_err() {
+        set_error_code(err::ssl::SSL_ERROR_BAD_MAC_READ);
+        let r = secstatus_to_res(SECFailure);
+        assert!(r.is_err());
+        match r.unwrap_err() {
+            Error::NssError { name, code, desc } => {
+                assert_eq!(name, "SSL_ERROR_BAD_MAC_READ");
+                assert_eq!(code, -12273);
+                assert_eq!(
+                    desc,
+                    "SSL received a record with an incorrect Message Authentication Code."
+                );
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn is_err_zero_code() {
+        set_error_code(0);
+        let r = secstatus_to_res(SECFailure);
+        assert!(r.is_err());
+        match r.unwrap_err() {
+            Error::NssError { name, code, .. } => {
+                assert_eq!(name, "UNKNOWN_ERROR");
+                assert_eq!(code, 0);
+                // Note that we don't test |desc| here because that comes from
+                // strerror(0), which is platform-dependent.
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn blocked() {
+        set_error_code(err::nspr::PR_WOULD_BLOCK_ERROR);
+        let r = secstatus_to_res(SECFailure);
+        assert!(r.is_err());
+        assert!(is_blocked(&r));
+        match r.unwrap_err() {
+            Error::NssError { name, code, desc } => {
+                assert_eq!(name, "PR_WOULD_BLOCK_ERROR");
+                assert_eq!(code, -5998);
+                assert_eq!(desc, "The operation would have blocked");
+            }
+            _ => panic!("bad error type"),
+        }
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/exp.rs b/third_party/rust/neqo-crypto/src/exp.rs
new file mode 100644
index 0000000000..75867d80bb
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/exp.rs
@@ -0,0 +1,24 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[macro_export]
+macro_rules! experimental_api {
+    ( $n:ident ( $( $a:ident : $t:ty ),* $(,)? ) ) => {
+        #[allow(non_snake_case)]
+        #[allow(clippy::too_many_arguments)]
+        pub(crate) unsafe fn $n ( $( $a : $t ),* ) -> Result<(), $crate::err::Error> {
+            const EXP_FUNCTION: &str = stringify!($n);
+            let n = ::std::ffi::CString::new(EXP_FUNCTION)?;
+            let f = $crate::ssl::SSL_GetExperimentalAPI(n.as_ptr());
+            if f.is_null() {
+                return Err($crate::err::Error::InternalError);
+            }
+            let f: unsafe extern "C" fn( $( $t ),* ) -> $crate::ssl::SECStatus = ::std::mem::transmute(f);
+            let rv = f( $( $a ),* );
+            $crate::err::secstatus_to_res(rv)
+        }
+    };
+}
diff --git a/third_party/rust/neqo-crypto/src/ext.rs b/third_party/rust/neqo-crypto/src/ext.rs
new file mode 100644
index 0000000000..310e87a1b7
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/ext.rs
@@ -0,0 +1,169 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    cell::RefCell,
+    convert::TryFrom,
+    os::raw::{c_uint, c_void},
+    pin::Pin,
+    rc::Rc,
+};
+
+use crate::{
+    agentio::as_c_void,
+    constants::{Extension, HandshakeMessage, TLS_HS_CLIENT_HELLO, TLS_HS_ENCRYPTED_EXTENSIONS},
+    err::Res,
+    ssl::{
+        PRBool, PRFileDesc, SECFailure, SECStatus, SECSuccess, SSLAlertDescription,
+        SSLExtensionHandler, SSLExtensionWriter, SSLHandshakeType,
+    },
+};
+
+experimental_api!(SSL_InstallExtensionHooks(
+    fd: *mut PRFileDesc,
+    extension: u16,
+    writer: SSLExtensionWriter,
+    writer_arg: *mut c_void,
+    handler: SSLExtensionHandler,
+    handler_arg: *mut c_void,
+));
+
+pub enum ExtensionWriterResult {
+    Write(usize),
+    Skip,
+}
+
+pub enum ExtensionHandlerResult {
+    Ok,
+    Alert(crate::constants::Alert),
+}
+
+pub trait ExtensionHandler {
+    fn write(&mut self, msg: HandshakeMessage, _d: &mut [u8]) -> ExtensionWriterResult {
+        match msg {
+            TLS_HS_CLIENT_HELLO | TLS_HS_ENCRYPTED_EXTENSIONS => ExtensionWriterResult::Write(0),
+            _ => ExtensionWriterResult::Skip,
+        }
+    }
+
+    fn handle(&mut self, msg: HandshakeMessage, _d: &[u8]) -> ExtensionHandlerResult {
+        match msg {
+            TLS_HS_CLIENT_HELLO | TLS_HS_ENCRYPTED_EXTENSIONS => ExtensionHandlerResult::Ok,
+            _ => ExtensionHandlerResult::Alert(110), // unsupported_extension
+        }
+    }
+}
+
+type BoxedExtensionHandler = Box<Rc<RefCell<dyn ExtensionHandler>>>;
+
+pub struct ExtensionTracker {
+    extension: Extension,
+    handler: Pin<Box<BoxedExtensionHandler>>,
+}
+
+impl ExtensionTracker {
+    // Technically the as_mut() call here is the only unsafe bit,
+    // but don't call this function lightly.
+    unsafe fn wrap_handler_call<F, T>(arg: *mut c_void, f: F) -> T
+    where
+        F: FnOnce(&mut dyn ExtensionHandler) -> T,
+    {
+        let rc = arg.cast::<BoxedExtensionHandler>().as_mut().unwrap();
+        f(&mut *rc.borrow_mut())
+    }
+
+    #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
+    unsafe extern "C" fn extension_writer(
+        _fd: *mut PRFileDesc,
+        message: SSLHandshakeType::Type,
+        data: *mut u8,
+        len: *mut c_uint,
+        max_len: c_uint,
+        arg: *mut c_void,
+    ) -> PRBool {
+        let d = std::slice::from_raw_parts_mut(data, max_len as usize);
+        Self::wrap_handler_call(arg, |handler| {
+            // Cast is safe here because the message type is always part of the enum
+            match handler.write(message as HandshakeMessage, d) {
+                ExtensionWriterResult::Write(sz) => {
+                    *len = c_uint::try_from(sz).expect("integer overflow from extension writer");
+                    1
+                }
+                ExtensionWriterResult::Skip => 0,
+            }
+        })
+    }
+
+    unsafe extern "C" fn extension_handler(
+        _fd: *mut PRFileDesc,
+        message: SSLHandshakeType::Type,
+        data: *const u8,
+        len: c_uint,
+        alert: *mut SSLAlertDescription,
+        arg: *mut c_void,
+    ) -> SECStatus {
+        let d = std::slice::from_raw_parts(data, len as usize);
+        #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
+        Self::wrap_handler_call(arg, |handler| {
+            // Cast is safe here because the message type is always part of the enum
+            match handler.handle(message as HandshakeMessage, d) {
+                ExtensionHandlerResult::Ok => SECSuccess,
+                ExtensionHandlerResult::Alert(a) => {
+                    *alert = a;
+                    SECFailure
+                }
+            }
+        })
+    }
+
+    /// Use the provided handler to manage an extension.  This is quite unsafe.
+    ///
+    /// # Safety
+    ///
+    /// The holder of this `ExtensionTracker` needs to ensure that it lives at
+    /// least as long as the file descriptor, as NSS provides no way to remove
+    /// an extension handler once it is configured.
+    ///
+    /// # Errors
+    ///
+    /// If the underlying NSS API fails to register a handler.
+    pub unsafe fn new(
+        fd: *mut PRFileDesc,
+        extension: Extension,
+        handler: Rc<RefCell<dyn ExtensionHandler>>,
+    ) -> Res<Self> {
+        // The ergonomics here aren't great for users of this API, but it's
+        // horrific here. The pinned outer box gives us a stable pointer to the inner
+        // box.  This is the pointer that is passed to NSS.
+        //
+        // The inner box points to the reference-counted object.  This inner box is
+        // what we end up with a reference to in callbacks.  That extra wrapper around
+        // the Rc avoid any touching of reference counts in callbacks, which would
+        // inevitably lead to leaks as we don't control how many times the callback
+        // is invoked.
+        //
+        // This way, only this "outer" code deals with the reference count.
+        let mut tracker = Self {
+            extension,
+            handler: Box::pin(Box::new(handler)),
+        };
+        SSL_InstallExtensionHooks(
+            fd,
+            extension,
+            Some(Self::extension_writer),
+            as_c_void(&mut tracker.handler),
+            Some(Self::extension_handler),
+            as_c_void(&mut tracker.handler),
+        )?;
+        Ok(tracker)
+    }
+}
+
+impl std::fmt::Debug for ExtensionTracker {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "ExtensionTracker: {:?}", self.extension)
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/hkdf.rs b/third_party/rust/neqo-crypto/src/hkdf.rs
new file mode 100644
index 0000000000..e3cf77418c
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/hkdf.rs
@@ -0,0 +1,137 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    convert::TryFrom,
+    os::raw::{c_char, c_uint},
+    ptr::null_mut,
+};
+
+use crate::{
+    constants::{
+        Cipher, Version, TLS_AES_128_GCM_SHA256, TLS_AES_256_GCM_SHA384,
+        TLS_CHACHA20_POLY1305_SHA256, TLS_VERSION_1_3,
+    },
+    err::{Error, Res},
+    p11::{
+        random, Item, PK11Origin, PK11SymKey, PK11_ImportDataKey, Slot, SymKey, CKA_DERIVE,
+        CKM_HKDF_DERIVE, CK_ATTRIBUTE_TYPE, CK_MECHANISM_TYPE,
+    },
+};
+
+experimental_api!(SSL_HkdfExtract(
+    version: Version,
+    cipher: Cipher,
+    salt: *mut PK11SymKey,
+    ikm: *mut PK11SymKey,
+    prk: *mut *mut PK11SymKey,
+));
+experimental_api!(SSL_HkdfExpandLabel(
+    version: Version,
+    cipher: Cipher,
+    prk: *mut PK11SymKey,
+    handshake_hash: *const u8,
+    handshake_hash_len: c_uint,
+    label: *const c_char,
+    label_len: c_uint,
+    secret: *mut *mut PK11SymKey,
+));
+
+fn key_size(version: Version, cipher: Cipher) -> Res<usize> {
+    if version != TLS_VERSION_1_3 {
+        return Err(Error::UnsupportedVersion);
+    }
+    Ok(match cipher {
+        TLS_AES_128_GCM_SHA256 | TLS_CHACHA20_POLY1305_SHA256 => 32,
+        TLS_AES_256_GCM_SHA384 => 48,
+        _ => return Err(Error::UnsupportedCipher),
+    })
+}
+
+/// Generate a random key of the right size for the given suite.
+///
+/// # Errors
+///
+/// Only if NSS fails.
+pub fn generate_key(version: Version, cipher: Cipher) -> Res<SymKey> {
+    import_key(version, &random(key_size(version, cipher)?))
+}
+
+/// Import a symmetric key for use with HKDF.
+///
+/// # Errors
+///
+/// Errors returned if the key buffer is an incompatible size or the NSS functions fail.
+pub fn import_key(version: Version, buf: &[u8]) -> Res<SymKey> {
+    if version != TLS_VERSION_1_3 {
+        return Err(Error::UnsupportedVersion);
+    }
+    let slot = Slot::internal()?;
+    #[allow(clippy::useless_conversion)] // TODO: Remove when we bump the MSRV to 1.74.0.
+    let key_ptr = unsafe {
+        PK11_ImportDataKey(
+            *slot,
+            CK_MECHANISM_TYPE::from(CKM_HKDF_DERIVE),
+            PK11Origin::PK11_OriginUnwrap,
+            CK_ATTRIBUTE_TYPE::from(CKA_DERIVE),
+            &mut Item::wrap(buf),
+            null_mut(),
+        )
+    };
+    SymKey::from_ptr(key_ptr)
+}
+
+/// Extract a PRK from the given salt and IKM using the algorithm defined in RFC 5869.
+///
+/// # Errors
+///
+/// Errors returned if inputs are too large or the NSS functions fail.
+pub fn extract(
+    version: Version,
+    cipher: Cipher,
+    salt: Option<&SymKey>,
+    ikm: &SymKey,
+) -> Res<SymKey> {
+    let mut prk: *mut PK11SymKey = null_mut();
+    let salt_ptr: *mut PK11SymKey = match salt {
+        Some(s) => **s,
+        None => null_mut(),
+    };
+    unsafe { SSL_HkdfExtract(version, cipher, salt_ptr, **ikm, &mut prk) }?;
+    SymKey::from_ptr(prk)
+}
+
+/// Expand a PRK using the HKDF-Expand-Label function defined in RFC 8446.
+///
+/// # Errors
+///
+/// Errors returned if inputs are too large or the NSS functions fail.
+pub fn expand_label(
+    version: Version,
+    cipher: Cipher,
+    prk: &SymKey,
+    handshake_hash: &[u8],
+    label: &str,
+) -> Res<SymKey> {
+    let l = label.as_bytes();
+    let mut secret: *mut PK11SymKey = null_mut();
+
+    // Note that this doesn't allow for passing null() for the handshake hash.
+    // A zero-length slice produces an identical result.
+    unsafe {
+        SSL_HkdfExpandLabel(
+            version,
+            cipher,
+            **prk,
+            handshake_hash.as_ptr(),
+            c_uint::try_from(handshake_hash.len())?,
+            l.as_ptr().cast(),
+            c_uint::try_from(l.len())?,
+            &mut secret,
+        )
+    }?;
+    SymKey::from_ptr(secret)
+}
diff --git a/third_party/rust/neqo-crypto/src/hp.rs b/third_party/rust/neqo-crypto/src/hp.rs
new file mode 100644
index 0000000000..2479eff8f5
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/hp.rs
@@ -0,0 +1,203 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    cell::RefCell,
+    convert::TryFrom,
+    fmt::{self, Debug},
+    os::raw::{c_char, c_int, c_uint},
+    ptr::{addr_of_mut, null, null_mut},
+    rc::Rc,
+};
+
+use crate::{
+    constants::{
+        Cipher, Version, TLS_AES_128_GCM_SHA256, TLS_AES_256_GCM_SHA384,
+        TLS_CHACHA20_POLY1305_SHA256,
+    },
+    err::{secstatus_to_res, Error, Res},
+    p11::{
+        Context, Item, PK11SymKey, PK11_CipherOp, PK11_CreateContextBySymKey, PK11_Encrypt,
+        PK11_GetBlockSize, SymKey, CKA_ENCRYPT, CKM_AES_ECB, CKM_CHACHA20, CK_ATTRIBUTE_TYPE,
+        CK_CHACHA20_PARAMS, CK_MECHANISM_TYPE,
+    },
+};
+
+experimental_api!(SSL_HkdfExpandLabelWithMech(
+    version: Version,
+    cipher: Cipher,
+    prk: *mut PK11SymKey,
+    handshake_hash: *const u8,
+    handshake_hash_len: c_uint,
+    label: *const c_char,
+    label_len: c_uint,
+    mech: CK_MECHANISM_TYPE,
+    key_size: c_uint,
+    secret: *mut *mut PK11SymKey,
+));
+
+#[derive(Clone)]
+pub enum HpKey {
+    /// An AES encryption context.
+    /// Note: as we need to clone this object, we clone the pointer and
+    /// track references using `Rc`.  `PK11Context` can't be used with `PK11_CloneContext`
+    /// as that is not supported for these contexts.
+    Aes(Rc<RefCell<Context>>),
+    /// The ChaCha20 mask has to invoke a new PK11_Encrypt every time as it needs to
+    /// change the counter and nonce on each invocation.
+    Chacha(SymKey),
+}
+
+impl Debug for HpKey {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "HpKey")
+    }
+}
+
+impl HpKey {
+    const SAMPLE_SIZE: usize = 16;
+
+    /// QUIC-specific API for extracting a header-protection key.
+    ///
+    /// # Errors
+    ///
+    /// Errors if HKDF fails or if the label is too long to fit in a `c_uint`.
+    ///
+    /// # Panics
+    ///
+    /// When `cipher` is not known to this code.
+    #[allow(clippy::cast_sign_loss)] // Cast for PK11_GetBlockSize is safe.
+    pub fn extract(version: Version, cipher: Cipher, prk: &SymKey, label: &str) -> Res<Self> {
+        const ZERO: &[u8] = &[0; 12];
+
+        let l = label.as_bytes();
+        let mut secret: *mut PK11SymKey = null_mut();
+
+        #[allow(clippy::useless_conversion)] // TODO: Remove when we bump the MSRV to 1.74.0.
+        let (mech, key_size) = match cipher {
+            TLS_AES_128_GCM_SHA256 => (CK_MECHANISM_TYPE::from(CKM_AES_ECB), 16),
+            TLS_AES_256_GCM_SHA384 => (CK_MECHANISM_TYPE::from(CKM_AES_ECB), 32),
+            TLS_CHACHA20_POLY1305_SHA256 => (CK_MECHANISM_TYPE::from(CKM_CHACHA20), 32),
+            _ => unreachable!(),
+        };
+
+        // Note that this doesn't allow for passing null() for the handshake hash.
+        // A zero-length slice produces an identical result.
+        unsafe {
+            SSL_HkdfExpandLabelWithMech(
+                version,
+                cipher,
+                **prk,
+                null(),
+                0,
+                l.as_ptr().cast(),
+                c_uint::try_from(l.len())?,
+                mech,
+                key_size,
+                &mut secret,
+            )
+        }?;
+        let key = SymKey::from_ptr(secret).or(Err(Error::HkdfError))?;
+
+        let res = match cipher {
+            TLS_AES_128_GCM_SHA256 | TLS_AES_256_GCM_SHA384 => {
+                // TODO: Remove when we bump the MSRV to 1.74.0.
+                #[allow(clippy::useless_conversion)]
+                let context_ptr = unsafe {
+                    PK11_CreateContextBySymKey(
+                        mech,
+                        CK_ATTRIBUTE_TYPE::from(CKA_ENCRYPT),
+                        *key,
+                        &Item::wrap(&ZERO[..0]), // Borrow a zero-length slice of ZERO.
+                    )
+                };
+                let context = Context::from_ptr(context_ptr).or(Err(Error::CipherInitFailure))?;
+                Self::Aes(Rc::new(RefCell::new(context)))
+            }
+            TLS_CHACHA20_POLY1305_SHA256 => Self::Chacha(key),
+            _ => unreachable!(),
+        };
+
+        debug_assert_eq!(
+            res.block_size(),
+            usize::try_from(unsafe { PK11_GetBlockSize(mech, null_mut()) }).unwrap()
+        );
+        Ok(res)
+    }
+
+    /// Get the sample size, which is also the output size.
+    #[must_use]
+    #[allow(clippy::unused_self)] // To maintain an API contract.
+    pub fn sample_size(&self) -> usize {
+        Self::SAMPLE_SIZE
+    }
+
+    fn block_size(&self) -> usize {
+        match self {
+            Self::Aes(_) => 16,
+            Self::Chacha(_) => 64,
+        }
+    }
+
+    /// Generate a header protection mask for QUIC.
+    ///
+    /// # Errors
+    ///
+    /// An error is returned if the NSS functions fail; a sample of the
+    /// wrong size is the obvious cause.
+    ///
+    /// # Panics
+    ///
+    /// When the mechanism for our key is not supported.
+    pub fn mask(&self, sample: &[u8]) -> Res<Vec<u8>> {
+        let mut output = vec![0_u8; self.block_size()];
+
+        match self {
+            Self::Aes(context) => {
+                let mut output_len: c_int = 0;
+                secstatus_to_res(unsafe {
+                    PK11_CipherOp(
+                        **context.borrow_mut(),
+                        output.as_mut_ptr(),
+                        &mut output_len,
+                        c_int::try_from(output.len())?,
+                        sample[..Self::SAMPLE_SIZE].as_ptr().cast(),
+                        c_int::try_from(Self::SAMPLE_SIZE).unwrap(),
+                    )
+                })?;
+                assert_eq!(usize::try_from(output_len).unwrap(), output.len());
+                Ok(output)
+            }
+
+            Self::Chacha(key) => {
+                let params: CK_CHACHA20_PARAMS = CK_CHACHA20_PARAMS {
+                    pBlockCounter: sample.as_ptr().cast_mut(),
+                    blockCounterBits: 32,
+                    pNonce: sample[4..Self::SAMPLE_SIZE].as_ptr().cast_mut(),
+                    ulNonceBits: 96,
+                };
+                let mut output_len: c_uint = 0;
+                let mut param_item = Item::wrap_struct(&params);
+                // TODO: Remove when we bump the MSRV to 1.74.0.
+                #[allow(clippy::useless_conversion)]
+                secstatus_to_res(unsafe {
+                    PK11_Encrypt(
+                        **key,
+                        CK_MECHANISM_TYPE::from(CKM_CHACHA20),
+                        addr_of_mut!(param_item),
+                        output[..].as_mut_ptr(),
+                        &mut output_len,
+                        c_uint::try_from(output.len())?,
+                        output[..].as_ptr(),
+                        c_uint::try_from(output.len())?,
+                    )
+                })?;
+                assert_eq!(usize::try_from(output_len).unwrap(), output.len());
+                Ok(output)
+            }
+        }
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/lib.rs b/third_party/rust/neqo-crypto/src/lib.rs
new file mode 100644
index 0000000000..05424ee1f3
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/lib.rs
@@ -0,0 +1,208 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![cfg_attr(feature = "deny-warnings", deny(warnings))]
+#![warn(clippy::pedantic)]
+// Bindgen auto generated code
+// won't adhere to the clippy rules below
+#![allow(clippy::module_name_repetitions)]
+#![allow(clippy::unseparated_literal_suffix)]
+#![allow(clippy::used_underscore_binding)]
+
+mod aead;
+#[cfg(feature = "fuzzing")]
+mod aead_fuzzing;
+pub mod agent;
+mod agentio;
+mod auth;
+mod cert;
+pub mod constants;
+mod ech;
+mod err;
+#[macro_use]
+mod exp;
+pub mod ext;
+pub mod hkdf;
+pub mod hp;
+mod once;
+#[macro_use]
+mod p11;
+mod prio;
+mod replay;
+mod secrets;
+pub mod selfencrypt;
+mod ssl;
+mod time;
+
+use std::{
+    ffi::CString,
+    path::{Path, PathBuf},
+    ptr::null,
+};
+
+#[cfg(not(feature = "fuzzing"))]
+pub use self::aead::RealAead as Aead;
+#[cfg(feature = "fuzzing")]
+pub use self::aead::RealAead;
+#[cfg(feature = "fuzzing")]
+pub use self::aead_fuzzing::FuzzingAead as Aead;
+use self::once::OnceResult;
+pub use self::{
+    agent::{
+        Agent, AllowZeroRtt, Client, HandshakeState, Record, RecordList, ResumptionToken,
+        SecretAgent, SecretAgentInfo, SecretAgentPreInfo, Server, ZeroRttCheckResult,
+        ZeroRttChecker,
+    },
+    auth::AuthenticationStatus,
+    constants::*,
+    ech::{
+        encode_config as encode_ech_config, generate_keys as generate_ech_keys, AeadId, KdfId,
+        KemId, SymmetricSuite,
+    },
+    err::{Error, PRErrorCode, Res},
+    ext::{ExtensionHandler, ExtensionHandlerResult, ExtensionWriterResult},
+    p11::{random, PrivateKey, PublicKey, SymKey},
+    replay::AntiReplay,
+    secrets::SecretDirection,
+    ssl::Opt,
+};
+
+const MINIMUM_NSS_VERSION: &str = "3.97";
+
+#[allow(non_upper_case_globals, clippy::redundant_static_lifetimes)]
+#[allow(clippy::upper_case_acronyms)]
+#[allow(unknown_lints, clippy::borrow_as_ptr)]
+mod nss {
+    include!(concat!(env!("OUT_DIR"), "/nss_init.rs"));
+}
+
+// Need to map the types through.
+fn secstatus_to_res(code: nss::SECStatus) -> Res<()> {
+    crate::err::secstatus_to_res(code as crate::ssl::SECStatus)
+}
+
+enum NssLoaded {
+    External,
+    NoDb,
+    Db(Box<Path>),
+}
+
+impl Drop for NssLoaded {
+    fn drop(&mut self) {
+        if !matches!(self, Self::External) {
+            unsafe {
+                secstatus_to_res(nss::NSS_Shutdown()).expect("NSS Shutdown failed");
+            }
+        }
+    }
+}
+
+static mut INITIALIZED: OnceResult<NssLoaded> = OnceResult::new();
+
+fn already_initialized() -> bool {
+    unsafe { nss::NSS_IsInitialized() != 0 }
+}
+
+fn version_check() {
+    let min_ver = CString::new(MINIMUM_NSS_VERSION).unwrap();
+    assert_ne!(
+        unsafe { nss::NSS_VersionCheck(min_ver.as_ptr()) },
+        0,
+        "Minimum NSS version of {MINIMUM_NSS_VERSION} not supported",
+    );
+}
+
+/// Initialize NSS.  This only executes the initialization routines once, so if there is any chance
+/// that
+///
+/// # Panics
+///
+/// When NSS initialization fails.
+pub fn init() {
+    // Set time zero.
+    time::init();
+    unsafe {
+        INITIALIZED.call_once(|| {
+            version_check();
+            if already_initialized() {
+                return NssLoaded::External;
+            }
+
+            secstatus_to_res(nss::NSS_NoDB_Init(null())).expect("NSS_NoDB_Init failed");
+            secstatus_to_res(nss::NSS_SetDomesticPolicy()).expect("NSS_SetDomesticPolicy failed");
+
+            NssLoaded::NoDb
+        });
+    }
+}
+
+/// This enables SSLTRACE by calling a simple, harmless function to trigger its
+/// side effects.  SSLTRACE is not enabled in NSS until a socket is made or
+/// global options are accessed.  Reading an option is the least impact approach.
+/// This allows us to use SSLTRACE in all of our unit tests and programs.
+#[cfg(debug_assertions)]
+fn enable_ssl_trace() {
+    let opt = ssl::Opt::Locking.as_int();
+    let mut v: ::std::os::raw::c_int = 0;
+    secstatus_to_res(unsafe { ssl::SSL_OptionGetDefault(opt, &mut v) })
+        .expect("SSL_OptionGetDefault failed");
+}
+
+/// Initialize with a database.
+///
+/// # Panics
+///
+/// If NSS cannot be initialized.
+pub fn init_db<P: Into<PathBuf>>(dir: P) {
+    time::init();
+    unsafe {
+        INITIALIZED.call_once(|| {
+            version_check();
+            if already_initialized() {
+                return NssLoaded::External;
+            }
+
+            let path = dir.into();
+            assert!(path.is_dir());
+            let pathstr = path.to_str().expect("path converts to string").to_string();
+            let dircstr = CString::new(pathstr).unwrap();
+            let empty = CString::new("").unwrap();
+            secstatus_to_res(nss::NSS_Initialize(
+                dircstr.as_ptr(),
+                empty.as_ptr(),
+                empty.as_ptr(),
+                nss::SECMOD_DB.as_ptr().cast(),
+                nss::NSS_INIT_READONLY,
+            ))
+            .expect("NSS_Initialize failed");
+
+            secstatus_to_res(nss::NSS_SetDomesticPolicy()).expect("NSS_SetDomesticPolicy failed");
+            secstatus_to_res(ssl::SSL_ConfigServerSessionIDCache(
+                1024,
+                0,
+                0,
+                dircstr.as_ptr(),
+            ))
+            .expect("SSL_ConfigServerSessionIDCache failed");
+
+            #[cfg(debug_assertions)]
+            enable_ssl_trace();
+
+            NssLoaded::Db(path.into_boxed_path())
+        });
+    }
+}
+
+/// # Panics
+///
+/// If NSS isn't initialized.
+pub fn assert_initialized() {
+    unsafe {
+        INITIALIZED.call_once(|| {
+            panic!("NSS not initialized with init or init_db");
+        });
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/once.rs b/third_party/rust/neqo-crypto/src/once.rs
new file mode 100644
index 0000000000..80657cfe26
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/once.rs
@@ -0,0 +1,44 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::sync::Once;
+
+#[allow(clippy::module_name_repetitions)]
+pub struct OnceResult<T> {
+    once: Once,
+    v: Option<T>,
+}
+
+impl<T> OnceResult<T> {
+    #[must_use]
+    pub const fn new() -> Self {
+        Self {
+            once: Once::new(),
+            v: None,
+        }
+    }
+
+    pub fn call_once<F: FnOnce() -> T>(&mut self, f: F) -> &T {
+        let v = &mut self.v;
+        self.once.call_once(|| {
+            *v = Some(f());
+        });
+        self.v.as_ref().unwrap()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::OnceResult;
+
+    static mut STATIC_ONCE_RESULT: OnceResult<u64> = OnceResult::new();
+
+    #[test]
+    fn static_update() {
+        assert_eq!(*unsafe { STATIC_ONCE_RESULT.call_once(|| 23) }, 23);
+        assert_eq!(*unsafe { STATIC_ONCE_RESULT.call_once(|| 24) }, 23);
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/p11.rs b/third_party/rust/neqo-crypto/src/p11.rs
new file mode 100644
index 0000000000..508d240062
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/p11.rs
@@ -0,0 +1,320 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(dead_code)]
+#![allow(non_upper_case_globals)]
+#![allow(non_camel_case_types)]
+#![allow(non_snake_case)]
+
+use std::{
+    convert::TryFrom,
+    mem,
+    ops::{Deref, DerefMut},
+    os::raw::{c_int, c_uint},
+    ptr::null_mut,
+};
+
+use neqo_common::hex_with_len;
+
+use crate::err::{secstatus_to_res, Error, Res};
+
+#[allow(clippy::upper_case_acronyms)]
+#[allow(clippy::unreadable_literal)]
+#[allow(unknown_lints, clippy::borrow_as_ptr)]
+mod nss_p11 {
+    include!(concat!(env!("OUT_DIR"), "/nss_p11.rs"));
+}
+
+pub use nss_p11::*;
+
+#[macro_export]
+macro_rules! scoped_ptr {
+    ($scoped:ident, $target:ty, $dtor:path) => {
+        pub struct $scoped {
+            ptr: *mut $target,
+        }
+
+        impl $scoped {
+            /// Create a new instance of `$scoped` from a pointer.
+            ///
+            /// # Errors
+            ///
+            /// When passed a null pointer generates an error.
+            pub fn from_ptr(ptr: *mut $target) -> Result<Self, $crate::err::Error> {
+                if ptr.is_null() {
+                    Err($crate::err::Error::last_nss_error())
+                } else {
+                    Ok(Self { ptr })
+                }
+            }
+        }
+
+        impl Deref for $scoped {
+            type Target = *mut $target;
+            #[must_use]
+            fn deref(&self) -> &*mut $target {
+                &self.ptr
+            }
+        }
+
+        impl DerefMut for $scoped {
+            fn deref_mut(&mut self) -> &mut *mut $target {
+                &mut self.ptr
+            }
+        }
+
+        impl Drop for $scoped {
+            #[allow(unused_must_use)]
+            fn drop(&mut self) {
+                unsafe { $dtor(self.ptr) };
+            }
+        }
+    };
+}
+
+scoped_ptr!(Certificate, CERTCertificate, CERT_DestroyCertificate);
+scoped_ptr!(CertList, CERTCertList, CERT_DestroyCertList);
+scoped_ptr!(PublicKey, SECKEYPublicKey, SECKEY_DestroyPublicKey);
+
+impl PublicKey {
+    /// Get the HPKE serialization of the public key.
+    ///
+    /// # Errors
+    ///
+    /// When the key cannot be exported, which can be because the type is not supported.
+    ///
+    /// # Panics
+    ///
+    /// When keys are too large to fit in `c_uint/usize`.  So only on programming error.
+    pub fn key_data(&self) -> Res<Vec<u8>> {
+        let mut buf = vec![0; 100];
+        let mut len: c_uint = 0;
+        secstatus_to_res(unsafe {
+            PK11_HPKE_Serialize(
+                **self,
+                buf.as_mut_ptr(),
+                &mut len,
+                c_uint::try_from(buf.len()).unwrap(),
+            )
+        })?;
+        buf.truncate(usize::try_from(len).unwrap());
+        Ok(buf)
+    }
+}
+
+impl Clone for PublicKey {
+    #[must_use]
+    fn clone(&self) -> Self {
+        let ptr = unsafe { SECKEY_CopyPublicKey(self.ptr) };
+        assert!(!ptr.is_null());
+        Self { ptr }
+    }
+}
+
+impl std::fmt::Debug for PublicKey {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        if let Ok(b) = self.key_data() {
+            write!(f, "PublicKey {}", hex_with_len(b))
+        } else {
+            write!(f, "Opaque PublicKey")
+        }
+    }
+}
+
+scoped_ptr!(PrivateKey, SECKEYPrivateKey, SECKEY_DestroyPrivateKey);
+
+impl PrivateKey {
+    /// Get the bits of the private key.
+    ///
+    /// # Errors
+    ///
+    /// When the key cannot be exported, which can be because the type is not supported
+    /// or because the key data cannot be extracted from the PKCS#11 module.
+    ///
+    /// # Panics
+    ///
+    /// When the values are too large to fit.  So never.
+    pub fn key_data(&self) -> Res<Vec<u8>> {
+        let mut key_item = Item::make_empty();
+        #[allow(clippy::useless_conversion)] // TODO: Remove when we bump the MSRV to 1.74.0.
+        secstatus_to_res(unsafe {
+            PK11_ReadRawAttribute(
+                PK11ObjectType::PK11_TypePrivKey,
+                (**self).cast(),
+                CK_ATTRIBUTE_TYPE::from(CKA_VALUE),
+                &mut key_item,
+            )
+        })?;
+        let slc = unsafe {
+            std::slice::from_raw_parts(key_item.data, usize::try_from(key_item.len).unwrap())
+        };
+        let key = Vec::from(slc);
+        // The data that `key_item` refers to needs to be freed, but we can't
+        // use the scoped `Item` implementation.  This is OK as long as nothing
+        // panics between `PK11_ReadRawAttribute` succeeding and here.
+        unsafe {
+            SECITEM_FreeItem(&mut key_item, PRBool::from(false));
+        }
+        Ok(key)
+    }
+}
+unsafe impl Send for PrivateKey {}
+
+impl Clone for PrivateKey {
+    #[must_use]
+    fn clone(&self) -> Self {
+        let ptr = unsafe { SECKEY_CopyPrivateKey(self.ptr) };
+        assert!(!ptr.is_null());
+        Self { ptr }
+    }
+}
+
+impl std::fmt::Debug for PrivateKey {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        if let Ok(b) = self.key_data() {
+            write!(f, "PrivateKey {}", hex_with_len(b))
+        } else {
+            write!(f, "Opaque PrivateKey")
+        }
+    }
+}
+
+scoped_ptr!(Slot, PK11SlotInfo, PK11_FreeSlot);
+
+impl Slot {
+    pub fn internal() -> Res<Self> {
+        let p = unsafe { PK11_GetInternalSlot() };
+        Slot::from_ptr(p)
+    }
+}
+
+scoped_ptr!(SymKey, PK11SymKey, PK11_FreeSymKey);
+
+impl SymKey {
+    /// You really don't want to use this.
+    ///
+    /// # Errors
+    ///
+    /// Internal errors in case of failures in NSS.
+    pub fn as_bytes(&self) -> Res<&[u8]> {
+        secstatus_to_res(unsafe { PK11_ExtractKeyValue(self.ptr) })?;
+
+        let key_item = unsafe { PK11_GetKeyData(self.ptr) };
+        // This is accessing a value attached to the key, so we can treat this as a borrow.
+        match unsafe { key_item.as_mut() } {
+            None => Err(Error::InternalError),
+            Some(key) => Ok(unsafe { std::slice::from_raw_parts(key.data, key.len as usize) }),
+        }
+    }
+}
+
+impl Clone for SymKey {
+    #[must_use]
+    fn clone(&self) -> Self {
+        let ptr = unsafe { PK11_ReferenceSymKey(self.ptr) };
+        assert!(!ptr.is_null());
+        Self { ptr }
+    }
+}
+
+impl std::fmt::Debug for SymKey {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        if let Ok(b) = self.as_bytes() {
+            write!(f, "SymKey {}", hex_with_len(b))
+        } else {
+            write!(f, "Opaque SymKey")
+        }
+    }
+}
+
+unsafe fn destroy_pk11_context(ctxt: *mut PK11Context) {
+    PK11_DestroyContext(ctxt, PRBool::from(true));
+}
+scoped_ptr!(Context, PK11Context, destroy_pk11_context);
+
+unsafe fn destroy_secitem(item: *mut SECItem) {
+    SECITEM_FreeItem(item, PRBool::from(true));
+}
+scoped_ptr!(Item, SECItem, destroy_secitem);
+
+impl Item {
+    /// Create a wrapper for a slice of this object.
+    /// Creating this object is technically safe, but using it is extremely dangerous.
+    /// Minimally, it can only be passed as a `const SECItem*` argument to functions,
+    /// or those that treat their argument as `const`.
+    pub fn wrap(buf: &[u8]) -> SECItem {
+        SECItem {
+            type_: SECItemType::siBuffer,
+            data: buf.as_ptr().cast_mut(),
+            len: c_uint::try_from(buf.len()).unwrap(),
+        }
+    }
+
+    /// Create a wrapper for a struct.
+    /// Creating this object is technically safe, but using it is extremely dangerous.
+    /// Minimally, it can only be passed as a `const SECItem*` argument to functions,
+    /// or those that treat their argument as `const`.
+    pub fn wrap_struct<T>(v: &T) -> SECItem {
+        let data: *const T = v;
+        SECItem {
+            type_: SECItemType::siBuffer,
+            data: data.cast_mut().cast(),
+            len: c_uint::try_from(mem::size_of::<T>()).unwrap(),
+        }
+    }
+
+    /// Make an empty `SECItem` for passing as a mutable `SECItem*` argument.
+    pub fn make_empty() -> SECItem {
+        SECItem {
+            type_: SECItemType::siBuffer,
+            data: null_mut(),
+            len: 0,
+        }
+    }
+
+    /// This dereferences the pointer held by the item and makes a copy of the
+    /// content that is referenced there.
+    ///
+    /// # Safety
+    ///
+    /// This dereferences two pointers.  It doesn't get much less safe.
+    pub unsafe fn into_vec(self) -> Vec<u8> {
+        let b = self.ptr.as_ref().unwrap();
+        // Sanity check the type, as some types don't count bytes in `Item::len`.
+        assert_eq!(b.type_, SECItemType::siBuffer);
+        let slc = std::slice::from_raw_parts(b.data, usize::try_from(b.len).unwrap());
+        Vec::from(slc)
+    }
+}
+
+/// Generate a randomized buffer.
+///
+/// # Panics
+///
+/// When `size` is too large or NSS fails.
+#[must_use]
+pub fn random(size: usize) -> Vec<u8> {
+    let mut buf = vec![0; size];
+    secstatus_to_res(unsafe {
+        PK11_GenerateRandom(buf.as_mut_ptr(), c_int::try_from(buf.len()).unwrap())
+    })
+    .unwrap();
+    buf
+}
+
+#[cfg(test)]
+mod test {
+    use test_fixture::fixture_init;
+
+    use super::random;
+
+    #[test]
+    fn randomness() {
+        fixture_init();
+        // If this ever fails, there is either a bug, or it's time to buy a lottery ticket.
+        assert_ne!(random(16), random(16));
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/prio.rs b/third_party/rust/neqo-crypto/src/prio.rs
new file mode 100644
index 0000000000..527d8739c8
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/prio.rs
@@ -0,0 +1,25 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(clippy::upper_case_acronyms)]
+#![allow(
+    dead_code,
+    non_upper_case_globals,
+    non_snake_case,
+    clippy::cognitive_complexity,
+    clippy::empty_enum,
+    clippy::too_many_lines,
+    unknown_lints,
+    clippy::borrow_as_ptr
+)]
+
+include!(concat!(env!("OUT_DIR"), "/nspr_io.rs"));
+
+pub enum PRFileInfo {}
+pub enum PRFileInfo64 {}
+pub enum PRFilePrivate {}
+pub enum PRIOVec {}
+pub enum PRSendFileData {}
diff --git a/third_party/rust/neqo-crypto/src/replay.rs b/third_party/rust/neqo-crypto/src/replay.rs
new file mode 100644
index 0000000000..d4d3677f5c
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/replay.rs
@@ -0,0 +1,83 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{
+    convert::{TryFrom, TryInto},
+    ops::{Deref, DerefMut},
+    os::raw::c_uint,
+    ptr::null_mut,
+    time::{Duration, Instant},
+};
+
+use crate::{
+    err::Res,
+    ssl::PRFileDesc,
+    time::{Interval, PRTime, Time},
+};
+
+// This is an opaque struct in NSS.
+#[allow(clippy::upper_case_acronyms)]
+#[allow(clippy::empty_enum)]
+pub enum SSLAntiReplayContext {}
+
+experimental_api!(SSL_CreateAntiReplayContext(
+    now: PRTime,
+    window: PRTime,
+    k: c_uint,
+    bits: c_uint,
+    ctx: *mut *mut SSLAntiReplayContext,
+));
+experimental_api!(SSL_ReleaseAntiReplayContext(ctx: *mut SSLAntiReplayContext));
+experimental_api!(SSL_SetAntiReplayContext(
+    fd: *mut PRFileDesc,
+    ctx: *mut SSLAntiReplayContext,
+));
+
+scoped_ptr!(
+    AntiReplayContext,
+    SSLAntiReplayContext,
+    SSL_ReleaseAntiReplayContext
+);
+
+/// `AntiReplay` is used by servers when processing 0-RTT handshakes.
+/// It limits the exposure of servers to replay attack by rejecting 0-RTT
+/// if it appears to be a replay.  There is a false-positive rate that can be
+/// managed by tuning the parameters used to create the context.
+#[allow(clippy::module_name_repetitions)]
+pub struct AntiReplay {
+    ctx: AntiReplayContext,
+}
+
+impl AntiReplay {
+    /// Make a new anti-replay context.
+    /// See the documentation in NSS for advice on how to set these values.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if `now` is in the past relative to our baseline or
+    /// NSS is unable to generate an anti-replay context.
+    pub fn new(now: Instant, window: Duration, k: usize, bits: usize) -> Res<Self> {
+        let mut ctx: *mut SSLAntiReplayContext = null_mut();
+        unsafe {
+            SSL_CreateAntiReplayContext(
+                Time::from(now).try_into()?,
+                Interval::from(window).try_into()?,
+                c_uint::try_from(k)?,
+                c_uint::try_from(bits)?,
+                &mut ctx,
+            )
+        }?;
+
+        Ok(Self {
+            ctx: AntiReplayContext::from_ptr(ctx)?,
+        })
+    }
+
+    /// Configure the provided socket with this anti-replay context.
+    pub(crate) fn config_socket(&self, fd: *mut PRFileDesc) -> Res<()> {
+        unsafe { SSL_SetAntiReplayContext(fd, *self.ctx) }
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/result.rs b/third_party/rust/neqo-crypto/src/result.rs
new file mode 100644
index 0000000000..e304fcea7f
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/result.rs
@@ -0,0 +1,135 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use crate::{
+    err::{nspr, Error, PR_ErrorToName, PR_ErrorToString, PR_GetError, Res, PR_LANGUAGE_I_DEFAULT},
+    ssl,
+};
+
+use std::ffi::CStr;
+
+pub fn result(rv: ssl::SECStatus) -> Res<()> {
+    _ = result_helper(rv, false)?;
+    Ok(())
+}
+
+pub fn result_or_blocked(rv: ssl::SECStatus) -> Res<bool> {
+    result_helper(rv, true)
+}
+
+fn wrap_str_fn<F>(f: F, dflt: &str) -> String
+where
+    F: FnOnce() -> *const i8,
+{
+    unsafe {
+        let p = f();
+        if p.is_null() {
+            return dflt.to_string();
+        }
+        CStr::from_ptr(p).to_string_lossy().into_owned()
+    }
+}
+
+fn result_helper(rv: ssl::SECStatus, allow_blocked: bool) -> Res<bool> {
+    if rv == ssl::_SECStatus_SECSuccess {
+        return Ok(false);
+    }
+
+    let code = unsafe { PR_GetError() };
+    if allow_blocked && code == nspr::PR_WOULD_BLOCK_ERROR {
+        return Ok(true);
+    }
+
+    let name = wrap_str_fn(|| unsafe { PR_ErrorToName(code) }, "UNKNOWN_ERROR");
+    let desc = wrap_str_fn(
+        || unsafe { PR_ErrorToString(code, PR_LANGUAGE_I_DEFAULT) },
+        "...",
+    );
+    Err(Error::NssError { name, code, desc })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{result, result_or_blocked};
+    use crate::{
+        err::{self, nspr, Error, PRErrorCode, PR_SetError},
+        ssl,
+    };
+    use test_fixture::fixture_init;
+
+    fn set_error_code(code: PRErrorCode) {
+        unsafe { PR_SetError(code, 0) };
+    }
+
+    #[test]
+    fn is_ok() {
+        assert!(result(ssl::SECSuccess).is_ok());
+    }
+
+    #[test]
+    fn is_err() {
+        // This code doesn't work without initializing NSS first.
+        fixture_init();
+
+        set_error_code(err::ssl::SSL_ERROR_BAD_MAC_READ);
+        let r = result(ssl::SECFailure);
+        assert!(r.is_err());
+        match r.unwrap_err() {
+            Error::NssError { name, code, desc } => {
+                assert_eq!(name, "SSL_ERROR_BAD_MAC_READ");
+                assert_eq!(code, -12273);
+                assert_eq!(
+                    desc,
+                    "SSL received a record with an incorrect Message Authentication Code."
+                );
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn is_err_zero_code() {
+        // This code doesn't work without initializing NSS first.
+        fixture_init();
+
+        set_error_code(0);
+        let r = result(ssl::SECFailure);
+        assert!(r.is_err());
+        match r.unwrap_err() {
+            Error::NssError { name, code, .. } => {
+                assert_eq!(name, "UNKNOWN_ERROR");
+                assert_eq!(code, 0);
+                // Note that we don't test |desc| here because that comes from
+                // strerror(0), which is platform-dependent.
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn blocked_as_error() {
+        // This code doesn't work without initializing NSS first.
+        fixture_init();
+
+        set_error_code(nspr::PR_WOULD_BLOCK_ERROR);
+        let r = result(ssl::SECFailure);
+        assert!(r.is_err());
+        match r.unwrap_err() {
+            Error::NssError { name, code, desc } => {
+                assert_eq!(name, "PR_WOULD_BLOCK_ERROR");
+                assert_eq!(code, -5998);
+                assert_eq!(desc, "The operation would have blocked");
+            }
+            _ => panic!("bad error type"),
+        }
+    }
+
+    #[test]
+    fn is_blocked() {
+        set_error_code(nspr::PR_WOULD_BLOCK_ERROR);
+        assert!(result_or_blocked(ssl::SECFailure).unwrap());
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/secrets.rs b/third_party/rust/neqo-crypto/src/secrets.rs
new file mode 100644
index 0000000000..75677636b6
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/secrets.rs
@@ -0,0 +1,129 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::{os::raw::c_void, pin::Pin};
+
+use neqo_common::qdebug;
+
+use crate::{
+    agentio::as_c_void,
+    constants::Epoch,
+    err::Res,
+    p11::{PK11SymKey, PK11_ReferenceSymKey, SymKey},
+    ssl::{PRFileDesc, SSLSecretCallback, SSLSecretDirection},
+};
+
+experimental_api!(SSL_SecretCallback(
+    fd: *mut PRFileDesc,
+    cb: SSLSecretCallback,
+    arg: *mut c_void,
+));
+
+#[derive(Clone, Copy, Debug)]
+pub enum SecretDirection {
+    Read,
+    Write,
+}
+
+impl From<SSLSecretDirection::Type> for SecretDirection {
+    #[must_use]
+    fn from(dir: SSLSecretDirection::Type) -> Self {
+        match dir {
+            SSLSecretDirection::ssl_secret_read => Self::Read,
+            SSLSecretDirection::ssl_secret_write => Self::Write,
+            _ => unreachable!(),
+        }
+    }
+}
+
+#[derive(Debug, Default)]
+#[allow(clippy::module_name_repetitions)]
+pub struct DirectionalSecrets {
+    // We only need to maintain 3 secrets for the epochs used during the handshake.
+    secrets: [Option<SymKey>; 3],
+}
+
+impl DirectionalSecrets {
+    fn put(&mut self, epoch: Epoch, key: SymKey) {
+        assert!(epoch > 0);
+        let i = (epoch - 1) as usize;
+        assert!(i < self.secrets.len());
+        // assert!(self.secrets[i].is_none());
+        self.secrets[i] = Some(key);
+    }
+
+    pub fn take(&mut self, epoch: Epoch) -> Option<SymKey> {
+        assert!(epoch > 0);
+        let i = (epoch - 1) as usize;
+        assert!(i < self.secrets.len());
+        self.secrets[i].take()
+    }
+}
+
+#[derive(Debug, Default)]
+pub struct Secrets {
+    r: DirectionalSecrets,
+    w: DirectionalSecrets,
+}
+
+impl Secrets {
+    #[allow(clippy::unused_self)]
+    unsafe extern "C" fn secret_available(
+        _fd: *mut PRFileDesc,
+        epoch: u16,
+        dir: SSLSecretDirection::Type,
+        secret: *mut PK11SymKey,
+        arg: *mut c_void,
+    ) {
+        let secrets = arg.cast::<Self>().as_mut().unwrap();
+        secrets.put_raw(epoch, dir, secret);
+    }
+
+    fn put_raw(&mut self, epoch: Epoch, dir: SSLSecretDirection::Type, key_ptr: *mut PK11SymKey) {
+        let key_ptr = unsafe { PK11_ReferenceSymKey(key_ptr) };
+        let key = SymKey::from_ptr(key_ptr).expect("NSS shouldn't be passing out NULL secrets");
+        self.put(SecretDirection::from(dir), epoch, key);
+    }
+
+    fn put(&mut self, dir: SecretDirection, epoch: Epoch, key: SymKey) {
+        qdebug!("{:?} secret available for {:?}: {:?}", dir, epoch, key);
+        let keys = match dir {
+            SecretDirection::Read => &mut self.r,
+            SecretDirection::Write => &mut self.w,
+        };
+        keys.put(epoch, key);
+    }
+}
+
+#[derive(Debug)]
+pub struct SecretHolder {
+    secrets: Pin<Box<Secrets>>,
+}
+
+impl SecretHolder {
+    /// This registers with NSS.  The lifetime of this object needs to match the lifetime
+    /// of the connection, or bad things might happen.
+    pub fn register(&mut self, fd: *mut PRFileDesc) -> Res<()> {
+        let p = as_c_void(&mut self.secrets);
+        unsafe { SSL_SecretCallback(fd, Some(Secrets::secret_available), p) }
+    }
+
+    pub fn take_read(&mut self, epoch: Epoch) -> Option<SymKey> {
+        self.secrets.r.take(epoch)
+    }
+
+    pub fn take_write(&mut self, epoch: Epoch) -> Option<SymKey> {
+        self.secrets.w.take(epoch)
+    }
+}
+
+impl Default for SecretHolder {
+    fn default() -> Self {
+        Self {
+            secrets: Box::pin(Secrets::default()),
+        }
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/selfencrypt.rs b/third_party/rust/neqo-crypto/src/selfencrypt.rs
new file mode 100644
index 0000000000..b8a63153fd
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/selfencrypt.rs
@@ -0,0 +1,161 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::mem;
+
+use neqo_common::{hex, qinfo, qtrace, Encoder};
+
+use crate::{
+    constants::{Cipher, Version},
+    err::{Error, Res},
+    hkdf,
+    p11::{random, SymKey},
+    Aead,
+};
+
+#[derive(Debug)]
+pub struct SelfEncrypt {
+    version: Version,
+    cipher: Cipher,
+    key_id: u8,
+    key: SymKey,
+    old_key: Option<SymKey>,
+}
+
+impl SelfEncrypt {
+    const VERSION: u8 = 1;
+    const SALT_LENGTH: usize = 16;
+
+    /// # Errors
+    ///
+    /// Failure to generate a new HKDF key using NSS results in an error.
+    pub fn new(version: Version, cipher: Cipher) -> Res<Self> {
+        let key = hkdf::generate_key(version, cipher)?;
+        Ok(Self {
+            version,
+            cipher,
+            key_id: 0,
+            key,
+            old_key: None,
+        })
+    }
+
+    fn make_aead(&self, k: &SymKey, salt: &[u8]) -> Res<Aead> {
+        debug_assert_eq!(salt.len(), Self::SALT_LENGTH);
+        let salt = hkdf::import_key(self.version, salt)?;
+        let secret = hkdf::extract(self.version, self.cipher, Some(&salt), k)?;
+        Aead::new(false, self.version, self.cipher, &secret, "neqo self")
+    }
+
+    /// Rotate keys.  This causes any previous key that is being held to be replaced by the current
+    /// key.
+    ///
+    /// # Errors
+    ///
+    /// Failure to generate a new HKDF key using NSS results in an error.
+    pub fn rotate(&mut self) -> Res<()> {
+        let new_key = hkdf::generate_key(self.version, self.cipher)?;
+        self.old_key = Some(mem::replace(&mut self.key, new_key));
+        let (kid, _) = self.key_id.overflowing_add(1);
+        self.key_id = kid;
+        qinfo!(["SelfEncrypt"], "Rotated keys to {}", self.key_id);
+        Ok(())
+    }
+
+    /// Seal an item using the underlying key.  This produces a single buffer that contains
+    /// the encrypted `plaintext`, plus a version number and salt.
+    /// `aad` is only used as input to the AEAD, it is not included in the output; the
+    /// caller is responsible for carrying the AAD as appropriate.
+    ///
+    /// # Errors
+    ///
+    /// Failure to protect using NSS AEAD APIs produces an error.
+    pub fn seal(&self, aad: &[u8], plaintext: &[u8]) -> Res<Vec<u8>> {
+        // Format is:
+        // struct {
+        //   uint8 version;
+        //   uint8 key_id;
+        //   uint8 salt[16];
+        //   opaque aead_encrypted(plaintext)[length as expanded];
+        // };
+        // AAD covers the entire header, plus the value of the AAD parameter that is provided.
+        let salt = random(Self::SALT_LENGTH);
+        let cipher = self.make_aead(&self.key, &salt)?;
+        let encoded_len = 2 + salt.len() + plaintext.len() + cipher.expansion();
+
+        let mut enc = Encoder::with_capacity(encoded_len);
+        enc.encode_byte(Self::VERSION);
+        enc.encode_byte(self.key_id);
+        enc.encode(&salt);
+
+        let mut extended_aad = enc.clone();
+        extended_aad.encode(aad);
+
+        let offset = enc.len();
+        let mut output: Vec<u8> = enc.into();
+        output.resize(encoded_len, 0);
+        cipher.encrypt(0, extended_aad.as_ref(), plaintext, &mut output[offset..])?;
+        qtrace!(
+            ["SelfEncrypt"],
+            "seal {} {} -> {}",
+            hex(aad),
+            hex(plaintext),
+            hex(&output)
+        );
+        Ok(output)
+    }
+
+    fn select_key(&self, kid: u8) -> Option<&SymKey> {
+        if kid == self.key_id {
+            Some(&self.key)
+        } else {
+            let (prev_key_id, _) = self.key_id.overflowing_sub(1);
+            if kid == prev_key_id {
+                self.old_key.as_ref()
+            } else {
+                None
+            }
+        }
+    }
+
+    /// Open the protected `ciphertext`.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error when the self-encrypted object is invalid;
+    /// when the keys have been rotated; or when NSS fails.
+    #[allow(clippy::similar_names)] // aad is similar to aead
+    pub fn open(&self, aad: &[u8], ciphertext: &[u8]) -> Res<Vec<u8>> {
+        if ciphertext[0] != Self::VERSION {
+            return Err(Error::SelfEncryptFailure);
+        }
+        let Some(key) = self.select_key(ciphertext[1]) else {
+            return Err(Error::SelfEncryptFailure);
+        };
+        let offset = 2 + Self::SALT_LENGTH;
+
+        let mut extended_aad = Encoder::with_capacity(offset + aad.len());
+        extended_aad.encode(&ciphertext[0..offset]);
+        extended_aad.encode(aad);
+
+        let aead = self.make_aead(key, &ciphertext[2..offset])?;
+        // NSS insists on having extra space available for decryption.
+        let padded_len = ciphertext.len() - offset;
+        let mut output = vec![0; padded_len];
+        let decrypted =
+            aead.decrypt(0, extended_aad.as_ref(), &ciphertext[offset..], &mut output)?;
+        let final_len = decrypted.len();
+        output.truncate(final_len);
+        qtrace!(
+            ["SelfEncrypt"],
+            "open {} {} -> {}",
+            hex(aad),
+            hex(ciphertext),
+            hex(&output)
+        );
+        Ok(output)
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/ssl.rs b/third_party/rust/neqo-crypto/src/ssl.rs
new file mode 100644
index 0000000000..8aaacffae6
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/ssl.rs
@@ -0,0 +1,153 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(
+    dead_code,
+    non_upper_case_globals,
+    non_snake_case,
+    clippy::cognitive_complexity,
+    clippy::too_many_lines,
+    clippy::upper_case_acronyms,
+    unknown_lints,
+    clippy::borrow_as_ptr
+)]
+
+use std::os::raw::{c_uint, c_void};
+
+use crate::{
+    constants::Epoch,
+    err::{secstatus_to_res, Res},
+};
+
+include!(concat!(env!("OUT_DIR"), "/nss_ssl.rs"));
+mod SSLOption {
+    include!(concat!(env!("OUT_DIR"), "/nss_sslopt.rs"));
+}
+
+// I clearly don't understand how bindgen operates.
+#[allow(clippy::empty_enum)]
+pub enum PLArenaPool {}
+#[allow(clippy::empty_enum)]
+pub enum PRFileDesc {}
+
+// Remap some constants.
+pub const SECSuccess: SECStatus = _SECStatus_SECSuccess;
+pub const SECFailure: SECStatus = _SECStatus_SECFailure;
+
+#[derive(Debug, Copy, Clone)]
+pub enum Opt {
+    Locking,
+    Tickets,
+    OcspStapling,
+    Alpn,
+    ExtendedMasterSecret,
+    SignedCertificateTimestamps,
+    EarlyData,
+    RecordSizeLimit,
+    Tls13CompatMode,
+    HelloDowngradeCheck,
+    SuppressEndOfEarlyData,
+    Grease,
+}
+
+impl Opt {
+    // Cast is safe here because SSLOptions are within the i32 range
+    #[allow(clippy::cast_possible_wrap)]
+    pub(crate) fn as_int(self) -> PRInt32 {
+        let i = match self {
+            Self::Locking => SSLOption::SSL_NO_LOCKS,
+            Self::Tickets => SSLOption::SSL_ENABLE_SESSION_TICKETS,
+            Self::OcspStapling => SSLOption::SSL_ENABLE_OCSP_STAPLING,
+            Self::Alpn => SSLOption::SSL_ENABLE_ALPN,
+            Self::ExtendedMasterSecret => SSLOption::SSL_ENABLE_EXTENDED_MASTER_SECRET,
+            Self::SignedCertificateTimestamps => SSLOption::SSL_ENABLE_SIGNED_CERT_TIMESTAMPS,
+            Self::EarlyData => SSLOption::SSL_ENABLE_0RTT_DATA,
+            Self::RecordSizeLimit => SSLOption::SSL_RECORD_SIZE_LIMIT,
+            Self::Tls13CompatMode => SSLOption::SSL_ENABLE_TLS13_COMPAT_MODE,
+            Self::HelloDowngradeCheck => SSLOption::SSL_ENABLE_HELLO_DOWNGRADE_CHECK,
+            Self::SuppressEndOfEarlyData => SSLOption::SSL_SUPPRESS_END_OF_EARLY_DATA,
+            Self::Grease => SSLOption::SSL_ENABLE_GREASE,
+        };
+        i as PRInt32
+    }
+
+    // Some options are backwards, like SSL_NO_LOCKS, so use this to manage that.
+    fn map_enabled(self, enabled: bool) -> PRIntn {
+        let v = match self {
+            Self::Locking => !enabled,
+            _ => enabled,
+        };
+        PRIntn::from(v)
+    }
+
+    pub(crate) fn set(self, fd: *mut PRFileDesc, value: bool) -> Res<()> {
+        secstatus_to_res(unsafe { SSL_OptionSet(fd, self.as_int(), self.map_enabled(value)) })
+    }
+}
+
+experimental_api!(SSL_GetCurrentEpoch(
+    fd: *mut PRFileDesc,
+    read_epoch: *mut u16,
+    write_epoch: *mut u16,
+));
+experimental_api!(SSL_HelloRetryRequestCallback(
+    fd: *mut PRFileDesc,
+    cb: SSLHelloRetryRequestCallback,
+    arg: *mut c_void,
+));
+experimental_api!(SSL_RecordLayerWriteCallback(
+    fd: *mut PRFileDesc,
+    cb: SSLRecordWriteCallback,
+    arg: *mut c_void,
+));
+experimental_api!(SSL_RecordLayerData(
+    fd: *mut PRFileDesc,
+    epoch: Epoch,
+    ct: SSLContentType::Type,
+    data: *const u8,
+    len: c_uint,
+));
+experimental_api!(SSL_SendSessionTicket(
+    fd: *mut PRFileDesc,
+    extra: *const u8,
+    len: c_uint,
+));
+experimental_api!(SSL_SetMaxEarlyDataSize(fd: *mut PRFileDesc, size: u32));
+experimental_api!(SSL_SetResumptionToken(
+    fd: *mut PRFileDesc,
+    token: *const u8,
+    len: c_uint,
+));
+experimental_api!(SSL_SetResumptionTokenCallback(
+    fd: *mut PRFileDesc,
+    cb: SSLResumptionTokenCallback,
+    arg: *mut c_void,
+));
+
+experimental_api!(SSL_GetResumptionTokenInfo(
+    token: *const u8,
+    token_len: c_uint,
+    info: *mut SSLResumptionTokenInfo,
+    len: c_uint,
+));
+
+experimental_api!(SSL_DestroyResumptionTokenInfo(
+    info: *mut SSLResumptionTokenInfo,
+));
+
+#[cfg(test)]
+mod tests {
+    use super::{SSL_GetNumImplementedCiphers, SSL_NumImplementedCiphers};
+
+    #[test]
+    fn num_ciphers() {
+        assert!(unsafe { SSL_NumImplementedCiphers } > 0);
+        assert!(unsafe { SSL_GetNumImplementedCiphers() } > 0);
+        assert_eq!(unsafe { SSL_NumImplementedCiphers }, unsafe {
+            SSL_GetNumImplementedCiphers()
+        });
+    }
+}
diff --git a/third_party/rust/neqo-crypto/src/time.rs b/third_party/rust/neqo-crypto/src/time.rs
new file mode 100644
index 0000000000..84dbfdb4a5
--- /dev/null
+++ b/third_party/rust/neqo-crypto/src/time.rs
@@ -0,0 +1,259 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(clippy::upper_case_acronyms)]
+
+use std::{
+    boxed::Box,
+    convert::{TryFrom, TryInto},
+    ops::Deref,
+    os::raw::c_void,
+    pin::Pin,
+    time::{Duration, Instant},
+};
+
+use crate::{
+    agentio::as_c_void,
+    err::{Error, Res},
+    once::OnceResult,
+    ssl::{PRFileDesc, SSLTimeFunc},
+};
+
+include!(concat!(env!("OUT_DIR"), "/nspr_time.rs"));
+
+experimental_api!(SSL_SetTimeFunc(
+    fd: *mut PRFileDesc,
+    cb: SSLTimeFunc,
+    arg: *mut c_void,
+));
+
+/// This struct holds the zero time used for converting between `Instant` and `PRTime`.
+#[derive(Debug)]
+struct TimeZero {
+    instant: Instant,
+    prtime: PRTime,
+}
+
+impl TimeZero {
+    /// This function sets a baseline from an instance of `Instant`.
+    /// This allows for the possibility that code that uses these APIs will create
+    /// instances of `Instant` before any of this code is run.  If `Instant`s older than
+    /// `BASE_TIME` are used with these conversion functions, they will fail.
+    /// To avoid that, we make sure that this sets the base time using the first value
+    /// it sees if it is in the past.  If it is not, then use `Instant::now()` instead.
+    pub fn baseline(t: Instant) -> Self {
+        let now = Instant::now();
+        let prnow = unsafe { PR_Now() };
+
+        if now <= t {
+            // `t` is in the future, just use `now`.
+            Self {
+                instant: now,
+                prtime: prnow,
+            }
+        } else {
+            let elapsed = Interval::from(now.duration_since(now));
+            // An error from these unwrap functions would require
+            // ridiculously long application running time.
+            let prelapsed: PRTime = elapsed.try_into().unwrap();
+            Self {
+                instant: t,
+                prtime: prnow.checked_sub(prelapsed).unwrap(),
+            }
+        }
+    }
+}
+
+static mut BASE_TIME: OnceResult<TimeZero> = OnceResult::new();
+
+fn get_base() -> &'static TimeZero {
+    let f = || TimeZero {
+        instant: Instant::now(),
+        prtime: unsafe { PR_Now() },
+    };
+    unsafe { BASE_TIME.call_once(f) }
+}
+
+pub(crate) fn init() {
+    _ = get_base();
+}
+
+/// Time wraps Instant and provides conversion functions into `PRTime`.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct Time {
+    t: Instant,
+}
+
+impl Deref for Time {
+    type Target = Instant;
+    fn deref(&self) -> &Self::Target {
+        &self.t
+    }
+}
+
+impl From<Instant> for Time {
+    /// Convert from an Instant into a Time.
+    fn from(t: Instant) -> Self {
+        // Call `TimeZero::baseline(t)` so that time zero can be set.
+        let f = || TimeZero::baseline(t);
+        _ = unsafe { BASE_TIME.call_once(f) };
+        Self { t }
+    }
+}
+
+impl TryFrom<PRTime> for Time {
+    type Error = Error;
+    fn try_from(prtime: PRTime) -> Res<Self> {
+        let base = get_base();
+        if let Some(delta) = prtime.checked_sub(base.prtime) {
+            let d = Duration::from_micros(delta.try_into()?);
+            base.instant
+                .checked_add(d)
+                .map_or(Err(Error::TimeTravelError), |t| Ok(Self { t }))
+        } else {
+            Err(Error::TimeTravelError)
+        }
+    }
+}
+
+impl TryInto<PRTime> for Time {
+    type Error = Error;
+    fn try_into(self) -> Res<PRTime> {
+        let base = get_base();
+        let delta = self
+            .t
+            .checked_duration_since(base.instant)
+            .ok_or(Error::TimeTravelError)?;
+        if let Ok(d) = PRTime::try_from(delta.as_micros()) {
+            d.checked_add(base.prtime).ok_or(Error::TimeTravelError)
+        } else {
+            Err(Error::TimeTravelError)
+        }
+    }
+}
+
+impl From<Time> for Instant {
+    #[must_use]
+    fn from(t: Time) -> Self {
+        t.t
+    }
+}
+
+/// Interval wraps Duration and provides conversion functions into `PRTime`.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct Interval {
+    d: Duration,
+}
+
+impl Deref for Interval {
+    type Target = Duration;
+    fn deref(&self) -> &Self::Target {
+        &self.d
+    }
+}
+
+impl TryFrom<PRTime> for Interval {
+    type Error = Error;
+    fn try_from(prtime: PRTime) -> Res<Self> {
+        Ok(Self {
+            d: Duration::from_micros(u64::try_from(prtime)?),
+        })
+    }
+}
+
+impl From<Duration> for Interval {
+    fn from(d: Duration) -> Self {
+        Self { d }
+    }
+}
+
+impl TryInto<PRTime> for Interval {
+    type Error = Error;
+    fn try_into(self) -> Res<PRTime> {
+        Ok(PRTime::try_from(self.d.as_micros())?)
+    }
+}
+
+/// `TimeHolder` maintains a `PRTime` value in a form that is accessible to the TLS stack.
+#[derive(Debug)]
+pub struct TimeHolder {
+    t: Pin<Box<PRTime>>,
+}
+
+impl TimeHolder {
+    unsafe extern "C" fn time_func(arg: *mut c_void) -> PRTime {
+        let p = arg as *const PRTime;
+        *p.as_ref().unwrap()
+    }
+
+    pub fn bind(&mut self, fd: *mut PRFileDesc) -> Res<()> {
+        unsafe { SSL_SetTimeFunc(fd, Some(Self::time_func), as_c_void(&mut self.t)) }
+    }
+
+    pub fn set(&mut self, t: Instant) -> Res<()> {
+        *self.t = Time::from(t).try_into()?;
+        Ok(())
+    }
+}
+
+impl Default for TimeHolder {
+    fn default() -> Self {
+        TimeHolder { t: Box::pin(0) }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::{
+        convert::{TryFrom, TryInto},
+        time::{Duration, Instant},
+    };
+
+    use super::{get_base, init, Interval, PRTime, Time};
+    use crate::err::Res;
+
+    #[test]
+    fn convert_stable() {
+        init();
+        let now = Time::from(Instant::now());
+        let pr: PRTime = now.try_into().expect("convert to PRTime with truncation");
+        let t2 = Time::try_from(pr).expect("convert to Instant");
+        let pr2: PRTime = t2.try_into().expect("convert to PRTime again");
+        assert_eq!(pr, pr2);
+        let t3 = Time::try_from(pr2).expect("convert to Instant again");
+        assert_eq!(t2, t3);
+    }
+
+    #[test]
+    fn past_time() {
+        init();
+        let base = get_base();
+        assert!(Time::try_from(base.prtime - 1).is_err());
+    }
+
+    #[test]
+    fn negative_time() {
+        init();
+        assert!(Time::try_from(-1).is_err());
+    }
+
+    #[test]
+    fn negative_interval() {
+        init();
+        assert!(Interval::try_from(-1).is_err());
+    }
+
+    #[test]
+    // We allow replace_consts here because
+    // std::u64::max_value() isn't available
+    // in all of our targets
+    fn overflow_interval() {
+        init();
+        let interval = Interval::from(Duration::from_micros(u64::max_value()));
+        let res: Res<PRTime> = interval.try_into();
+        assert!(res.is_err());
+    }
+}